The unions and little people working for them are also part of the corrupt racket. It is at all levels, don't focus on one, the others will find ways to protect that, or at least buy them off so they don't point at something else
I agree there's corruption throughout, but there's some especially wrong about the top elected official being corrupt in this way that's especially bad.
Very visible role. Nominally in charge of keeping the city prosperous and functional. Someone who citizens pretty directly select for the role.
I don't doubt there's corruption at every level, but when the leader of the organization is enriching themselves and their buddies it's hard to expect anyone else to do anything else.
I don't think corruption can be addressed bottom up
It has to be addressed at all levels. The unions are the supporting the corrupt politicians who support too many workers on the job. So long as everyone goes "my corruption is small/worth it - what about" we will never get anywhere. People need to be willing to bite the hand that feeds them.