While I strongly agree with your broader point- payment processing is absolutely regulated at close to a utility-level. Congress sets the rates that Visa & Mastercard can charge for credit & debit cards via statute. That's getting pretty close to say electric utility levels of regulation

Even though they aren’t regulated as a utility, they are very highly regulated. The examples you gave are just highly-politicized examples of a now-common standard and practice that all processors operating in the US have been required to uphold (not that it was involuntary) for decades. That’s part of why Stripe and other Payment Facilitator services have exploded: it’s not easy to open a traditional payment processing account, and very easy to get it shut down for seemingly random reasons.

Despite the online fervor over this, payment processors are clearly within their legal rights to shut down payment processing for abuse - even if it is only suspected.