Why can't women time travel? —asks Anna Smith in The Guardian, in a rather interesting op-ed piece on science fiction. While focusing mostly on movies, she's got a good point; women are seldom the protagonists of first-person time travel stories, especially in cinema. And while I can think of a number of exceptions in written fantasy and paranormal romance, I'm coming up with pocket-lint in genre SF.
Here's your explanation: time travel fiction—when time travel is the focus of the story, rather than a means to support a plot twist regarding the mechanism of temporal travel (for example, The Men Who Murdered Mohammed, A Sound of Thunder)—is a travelogue; or rather, a Grand Tour through the exotic foreign climes of the past.
Now, there's something significant to note about tourism. From its origins in the aforementioned grand tour to the present day, it's a ritual of the privileged. The sons of the landed gentry would take a post-Oxbridge trek through France and Italy and, later, Greece, visiting sites of classical antiquity, polishing their foreign language skills, and socializing with the aristocracy. It gave them a cultural education that was unavailable at home. But relatively few people did it; prior to the advent of the age of steam, sea and land travel was expensive, slow, and somewhat perilous. To accomplish a grand tour required resources: notably time and money.
Even in this age of cheap travel and hotels everywhere, tourism is the defining characteristic of the comfortably off, of the middle and upper classes of the developed world. To be a tourist one must have a sufficiency of income such that one can claw back some time from the daily grind of hand-to-mouth labor, and spend one's savings on the expenses of travel and accommodation. Tourism is a luxury. The poor, the unemployed, and refugees may travel, but they do so for survival's sake: the indulgence of pure curiosity is expensive. To be a tourist is also to exercise the tourist's gaze: to place onesself outside the context of the society in which one travels, to observe it as a stranger, and in turn to reduce these locations to a spectacle, be it for education or entertainment.
The time travel story is a tale of tourism in the classical sense: an activity of the privileged, making spectacle of the past (and, occasionally, the Wellsian future). And women make poor time travelers because in the foreign countries of the past they lack the agency conferred by privilege.
When one is reading fiction for escapism, to identify with a protagonist who undergoes interesting experiences and personal development through travel to exotic and unusual places, one often seeks to identify with the privileged: with individuals who are not immiserated by their experiences. (Usually. There are exceptions.) But by and large women lacked autonomy and independent agency in past times. They lived under the twin yokes of biological determinism and cultural oppression; in societies where 30-50% of newborns never made it to their fifth birthday, where between 5% and 10% of pregnancies ended in maternal death, and where access to contraception was questionable at best: and in societies dominated by patriarchal hierarchies. Most women historically lived as second-class citizens, at best. Furthermore, laws reflected this, as did social norms. To put things in perspective: the legal rights of an Englishwoman of 1882 bear a closer equivalence to those of an Iranian woman in 1982 than most of us are comfortable thinking about. And how many western women of today would be comfortable vacationing in contemporary Iran?
This is not to suggest that the situation of women in the developed world today is perfect, or even acceptable. (Rape culture and discrimination and the systematic subordination of women remain rife: we've got a long way to go.) But there's a difference between what those of us in North America or Europe take for granted today, and cultures where rape is normalized through lack of sanctions (legal or social), or sexual harassment of strange women is considered unremarkable. And those are happening today: historically systematic enslavement for prostitution was institutionalized in some cultures. The unpalatable fact is that if you're a woman of today, most of our history is a Crap-Sack World dystopia, with added state (and church) decreed repression, a ubiquitous threat of sexual violence, and reproductive slavery on top.
Time travel tourist yarns that describe the depths of our historical depravity have to deal with the essential problem that their settings can be no less sexist than our past. And there are time travel novels about women that tackle this problem head-on, but they tend to make for grim reading. Because unless a woman was born into the upper 0.1% of the population, her life was pretty dystopian by modern standards: and even then it wasn't necessarily great. (Consider a semi-random example: Faustina the Younger. It's hard to get much more elite than the Empress of Rome, with effectively unlimited wealth and a loyal husband of 30 years who clearly mourned her passing. Even so: she died before her 50th birthday, exhausted after bearing 13 babies, only 6 of whom made it past their tenth—life was hard.)
Anyway, back to my thesis:
A young and intrepid male time traveler might experience a tour of the Great Times as an educational adventure; an equally young and intrepid female time traveler could count herself lucky if she merely ended up in a Magdalene Laundry. (There were plenty of worse places to land, horrifying though this might seem.)
For a female protagonist to successfully enjoy time travel as a form of tourism implies either that she has defensive resources that render her invulnerable to the depredations of the locals (a Culture knife missile up her sleeve should do the trick), or that she has acquired a privilege power-up—probably by way of cross-dressing, which shows up depressingly often as a get-out-of-time-jail-free card. (It's so common in the literature, in fact, that it's somewhere between a cliche and a full-blown sub-genre convention.) But in neither of these circumstances is she able to engage with the alien society from within: She remains an outsider. Her privilege delivers alienation, not engagement. There are rare exceptions—you can all stop yelling "Doomsday Book!" at me on twitter—but exceptions don't invalidate a general trend.
Lord Byron (the uber-tourist) might have joined his romantic Greek rebels in rising against the Turkish empire; Marty McFly might have taken to the stage for a high school hop and introduced the audience to rock'n'roll a decade too early: but Peggy-Sue Got Married because that's the only option that was available to her, because the time-tourism sub-genre is inherently sexist. I rest my case.