When people expect, with good reason, to be refused the use of public toilets, they relieve themselves in the street. Shop owners then see this and decide such people should be kept out of their businesses. Each side's response confirms the other's assumption, so the exclusion feeds itself.
What looks to passersby like an aimless crowd of down-and-outers can be an organized business with defined roles, hierarchies, rules, and self-policing. Only time spent behind the scenes reveals the structure under a surface that looks simple. These street workers can actually add to a neighborhood's order and safety rather than eroding it.
Even people earning very little from scavenged goods, or simply asking for money, see what they do as honorable. The line they draw is between working for a living and stealing. That distinction gives them self-respect and a claim to decency on the street.
The theory that one unrepaired sign of disorder invites more crime can get stretched from objects to people. Poor men working on the street are then policed as visible disorder in themselves, whether or not they do any harm. The underlying driver is often fear of certain kinds of men in shared spaces, not anything they have actually done.
On the sidewalk, the written rules that allow street vending can count for less than an officer's on-the-spot judgment. One officer, handed the actual text of the law, said it meant nothing to him right then and threatened arrest over 'attitude.' Competing claims to public space get settled by who holds authority in the moment, not by what the law says.