PayPal partnered up with Epoch in 2013 to allow adult transactions so they don't have to deal with the adult merchants directly. Epoch takes care of all the customer support, risk, compliance, fraud management, etc. It started with EU in 2013 and in the beginning of 2015 it was extended to world wide. They are the only company that PayPal made such a deal with and it's the only way to legally take PayPal payments for adult websites.
https://epoch.com/paypal/