They didn't really even try to stop it in the early days. You could setup an injectable immunomodulator merchant account in under 10 minutes with Square. People started entire pill mills using Square and Paypal. It was wild!
Similar to Turo who allowed the vehicles of their users to be used by weak KYC'd users. You never knew who was actually driving the vehicle.
I had loads of interesting conversations with Ex San Quentin prisoners, was riveting to listen to some of them talk about the crimes committed with all the fintech startups. Everything I thought I knew was wrong.
Paypal/Square Mafia's used cheap pension money of VC's to take their vig.