But the foremost problem is really payment processing. Next problems come "next" so to say. Think of a Swiss Army Knife. Just because it can act as a fork, as

But the foremost problem is really payment processing. Next problems come "next" so to say. Think of a Swiss Army Knife. Just because it can act as a fork, as a knife, as a spoon, (and so on): nor restaurants will present consumers with Swiss Army Knifes, nor consumers would appreciate it. Sometimes the direct and relatively simple is indeed more suitable/needed. Depends on the domain, sure.. which, in this case, I think it's really "actual payment" problem (not contracts etc).