I had one experience whereby I had to receive some payments from some foreign entity for both HSBC and revolut. I got stuck into weeks of wrangling with with revolut (similar to that of OP), and having been through that next time I used HSBC, who immediately allowed the payment.

Some businesses simply follow the regulation more closely then others. It's just a fact. Businesses are always making the trade off calculation as to fines Vs costs. For revolut a fine could be existential, for HSBC it is not. Therefore they behave differently. Fines are a cost of business and incumbent firms have helped design regulations with regulators in part to defend their market position. Of course, there is always what they say the regulations are for (e.g. money laundering prevention etc), but there is often a further motivation. This concept is not new and you can see it all around us in the multitude of state capture that exists in many places.