You need a merchant account from a high-risk processor, combined with a generic gateway like Authorize.Net. (Don't use their built in processor) The all in one solutions like Stripe or Adyen are convenient but they aren't what high-risk industries need.

I've wondered about this, too. The simple and unhelpful answer is because banks/CC companies are conservative and consider them high risk. So why is that? I've been able to find two factors: 1) associated (correctly or not) with the sex industry, which is taboo, possibly regulated or outright illegal. 2) high rate of chargebacks. Factors leading to high chargebacks could include no returns allowed and taboo/shame. Imagine an insecure partner finds a charge on a CC and the other partner claims they didn't purchase it, leading to a chargeback to support the lie.

Here is one of the better articles I found: https://instabill.com/do-adult-toys-fall-into-the-high-risk-...

The credit card networks have brand protection clauses in their operating procedures.

They likely don’t actually prohibit adult toys specifically but payment processors can be conservative in fear of having major disruptions from the networks.

Stripe's rules don't even make sense on this - OnlyFans uses Stripe somehow

That’s sad. We integrated Adyen like 5-6 years ago and this requirement was nowhere to be found. All I remember was their SDKs are difficult to integrate.