Mastercard doesn’t give a crap about weed, and aren’t trying to control anything. They don’t want to be a part of federally illegal transactions. They want to follow the law, because they’re a big business and it’s dangerous not to. This is simple a result of the fact that weed is federally illegal - any other move on mastercard’s part would be irresponsible at this time.
Your experience is way outside the norm. Usually it’s very straightforward.