> I have trouble to see the risk with processing payments for online porn.

Huge number of chargebacks. A previous employer of mine had a subsidiary that handled premium rate SMS and phone call billing, a lot of which was adult services. You'd see a huge amount of contested charges, for reasons such as:

* Buyer's remorse (get drunk, wake up the next day, realise you spent $500 on porn)

* Unsupervised minor - your kid "borrows" your credit card for some online "research"

* Outright fraud - stolen cards, etc.

This varies quite a bit. I was the CTO of a very large porn site in the mid-2000s and our chargeback rate was tiny - a small fraction of a percent. That fact didn't help us avoid high-risk categorization, though.

The only time I've ever suffered from "stolen id", not even cards or accounts, was with an online porn company that sold the account in arrears to a collections agency. The agency even admitted they had nothing linking me to the transactions other than my name, but demanded I pay up. A stern letter fixed the problem from my end.

I guess there are a lot of chargebacks from people entering their details for "trials" as well as stolen cards being used.

PornHub has an enormous problem with sexual trafficking and child abuse, which means that financing PornHub exposes you to serious legal liability (and an unambiguous moral responsibility). So it's not just institutional prudishness - online porn is full of vicious criminals.

Wow so I guess Facebook needs to be classified as high risk as well? Please don't spread misinformation like that.

No