I think there is a truth for a lot of women that is kind of side-stepped or ignored by the wave of "sex-positive" sex-promoting messages about female sexuality and enjoyment, female orgasms etc.
I think the truth is that, for many women* - regardless of good/bad lovers, orgasm or not, sex desire and pleasure ('payoff') is just not as high, compared to the effort/cost.
*NAWALT obviously
In the past that was used as an excuse not to bother, and sometimes even seen as a virtue "lie back and think of England". Which is why I completely understand the pushback about women being sexual beings, 'just as sexual as men', etc. I think that some are, but a good sizeable percentage certainly aren't.
I think there's an interesting discussion to be had about it if it wasn't often met with a measure of insult/offence - "YOU might be like that, but I love sex! What's wrong with you?! You must be doing it wrong." (not digging at any one person - pointing to society's general attitude).
I think 'social payoff' is part of it for men, a feeling of victory or accomplishment (notches on a bedpost, trophy items), whereas for many women there is often a bit more shaming involved (is there even a male equivalent for the word slut that is anywhere near as seethingly used? Never mind the more hateful terms like 'cum-dumpster')
Physical discomfort/risk usually leans more heavily to the female too - childbirth injuries, accidental injury (if partner is large/heavy, etc), female urinary issues, periods, fear of pregnancy...
Lots of reasons... I could go on and on, but I'll stop now!