Where I live (big city) there are numbers you can text and it's a different guy every time. It's like ordering pizza except you get in their car for the transaction. You are usually waiting 20min at most. The whole operation is eerily professional. Back in my home town it was a guy you knew who may or may not be around or that other guy your friend knew who's house you could swing by. For weed in particular you tend to get more of the small town style dealers even in big cities just cos it's nice and people are used to it but for hard drugs people don't care, they want their drugs in the most convenient way possible.
The first time I heard of this kind of system it was for black tar heroin distribution in the US from a specific Mexican town that basically franchised the drug trade. [1]
Super interesting stuff. Google Xalisco or pick up the book Dreamland for more.
