Banks are heavily regulated for a reason
Ideally a bank would capitalize on the underserved market and find a way to manage the risk.
This goes beyond risk control. Insurance has had this figured out for a long time. You can model the risk of porn chargebacks and charge fees accordingly that cover the increased risk of chargeback. Bank behavior towards adult entertainment is a reflection of prevailing attitude of society in which we live, which is frequently quite opposed to sex work. It's not a question of banks demanding much higher feels for legal adult services, they don't want them.
I think they can't do that.
I believe since the PATRIOT act was passed, the onus of fraud prevention was put on the financial companies, not the government.
This has caused a big rift in the "freedom to exchange currency with whoever whenever" crowd since the banks now have the authority (and are actively using it!) to push private companies into following their bidding.
A large part of Pornhub moving from an "anybody uploads" to "premium content only" was because the credit card processors didn't want to risk doing financial transactions with a company that could _POTENTIALLY_ be (meaning: unproven) hosting CSAM materials on their website... [1]
This was part of the reason OnlyFans was going to forbid adult content on their platform, because of issues with banks and payment processors. They were able to find one with more acceptable terms (although with higher transaction fees on the part of onlyfans) and were able to go back to providing paid adult content. (again, we'll never know the true reason why, but it's been the modus operandi of payment processors to axe anybody who they don't want on their platform.) [2]
Fun fact, credit card payment processors add individuals to their list of "people they don't want to do business with" - which is then shared with other payment processors [3] - a large one that's used by the majority of payment processors is the MATCH list ran by Mastercard.
[1] https://www.theverge.com/2020/12/10/22168240/mastercard-endi...
[2] https://www.theverge.com/2021/8/27/22641095/onlyfans-sex-wor...
[3] https://www.chargebackgurus.com/blog/mastercard-match-list-a...
It seems the feminist angle was more of a general anti-porn thing observed by a lawyer in the field. NCOSE, an evangelical group, apparently took credit for onlyfans's porn ban saying "The announcement made by OnlyFans that it will prohibit creators from posting material with sexually explicit conduct on its website comes after much advocacy from NCOSE, survivors and allies." They, along with Exodus Cry (another evangelical group) also lobbied Master Card to change their policies on porn