That makes sense, but doesn't the skidding wear the tires much faster?

Sure, but if you weren't doing it for the culture you'd keep that shit to a minimun and try to go with the flow more. There's some other considerations here, bike theft, all the other parts of a brake that aren't a brake part and could go wrong etc. My point is mainly that it wasn't birthed from being real fucking dumb, but real fucking poor.

And if your brakes break that doesn't stop you from delivering, you just don't have brakes now (until you're able to fix them) right?

Well if you don't need them, why have them in the first place?