People and places become disposable not by being thrown out of the city but by being held in a particular relation to it. As a group they are vital and necessary, but each one is expendable. Disposability is a harmful form of inclusion, not a state of being cast out.
In waste work, earnings act like a deodorant. The money carries none of the dirt of how it was earned. It also shields workers from the contempt of people who might otherwise look down on them.
Formal city cleaning depends on informal pickers, scavengers and recyclers working alongside it. The city uses their cheap labor but never acknowledges it. Without them the official waste authority would be too overwhelmed to function.
Authorities and aid groups run campaigns that teach pride in cleanliness and shame at mess. They use these feelings to get people to do the unpaid and low-paid work of making a city look modern. Feelings do the work that pipes and trucks cannot.
A government that promises to finally maintain the city presents itself as a break with past neglect. That promise of cleanliness and order is then used to justify top-down, authoritarian rule. It also decides which residents belong and which get evicted.