What with witches and wizards, fairies and sprites all flying, usually by broomstick, sometimes by boot power, sometimes by instant transportation (which carries the risk of all your bits not necessarily re-materializing the way they should), there has to be a set of rules that even the most wicked of witches is going to follow. Nobody likes a tailgating broomstick user. They tend to be obliterated. And a wicked witch is just going to want to get about her business without traffic problems getting in her way. (Well you would, wouldn't you?).
The fairy government update the Code annually as they've usually come across yet another incidence of sprite stupidity that has a direct effect on travel and transportation and the best way to stop it is outlaw it. Even if the sprites ignore such a ban, it is widely known that flouting the Code is a good way to get you (a) killed, (b) jailed and (c) put in the stocks for a wide variety of nasty smelling stuff to be thrown at you. The latter is considered a very good form of family entertainment. Most sprites would prefer the first two options, yes even (a), as ritual humiliation is not something they find easy to deal with.