Your first statement is flat out wrong. Illegality is actually a driver of prices in all sorts of activity. See drug prices now, alcohol during the Prohibition. (Also, and this is more of a style and culture matter, learn about run-on sentences. They're one of those things that got cut in us-landia colleges.)

Obviously, it is "not like a bank transfer". Then again, that you personally have never seen anything like it, makes no difference in its actual legitimacy or usefulness as a medium of transaction.