They've colluded with the US federal government in the past on those issues as well. "Operation Choke Point" was ostensibly about fraud, but included transactions related to firearms in its scope. As a result, several major banks and payment processors dropped legitimate firearms dealers. For a while it got to the point that I was helping a couple of local gun stores contract with "high risk" payment processors that also serve the porn industry and get set up.
To this day if you're on a gun forum and mention that you use Bank of America, people will pile on to tell you horror stories of both companies and individuals having their accounts closed and funds held for weeks or months after completely legal transactions. In one case in particular, they claimed it happened after buying a backpack at a gun store.
Again, these are 100% legitimate and legal businesses. Federally licensed (FFL) gun stores had trouble for years even keeping a working business account. It was clearly not about fraud, at least not in practice.
Politics completely aside, the financial landscape for gun stores today looks a lot like the cannabis industry: a few institutions are quietly known in those communities to allow them to operate, but many choose to do business only in cash and most prefer it if given the option. The porn industry is similar from what I can see.