That's not really the right way to look at it.

In terms of "harder" to qualify - it is way harder for males. A few years ago there was a study in one of the running magazines that showed as a <35 yr old it was almost 15x harder to qualify as a male than a female. The reason is that there are way more males who run than females. As male, you have to run a sub 3hr marathon - you basically have to be a borderline elite athlete. Running a sub 3 puts you in the <1% of male runners who run marathons. Of women who run marathons, approx 15% of them can run a sub 3:30. So comparatively speaking, it is almost 15x harder as a male than female to qualify (in the youngest age bracket).

It's pretty obvious, even anecdotally, in my opinion. I've been running for over a decade, and pretty much all of my female friends who take their training even mildly seriously qualify for BQ with ease.

Over time, as more of the overall female population runs, the gap will even itself out - but I'm guessing that won't be for at least a few decades (assuming BAA's long term goal is to have an even 50/50 split).