Technically it may be easy, but handling money would surely involve contact with banks, regulatory system, etc. and these things are never easy. And they are ve

Technically it may be easy, but handling money would surely involve contact with banks, regulatory system, etc. and these things are never easy. And they are very intolerant to mistakes, even innocent ones - imagine getting your bank account frozen because you failed to comply with some obscure regulatory filing and then being unable to do anything until some bureaucratic entity (which are known for their agility and excellent customer service) figures out whether or not you are a front for Columbian narcocartel? A startup won't survive such thing. I'm not saying it's not doable - but I suspect it's harder than it appears, if you don't want to rely on established payment processing infrastructure.