This would be quite a bit more than a slap on the wrist in the US, the City of New York does all its own maintenance on all its buses, railroad and subway trains.
Manufacturer interference would result in some of the most aggressive city lawyers grinding the manufacturer's headquarters into dust, legislatively.
I can't believe it'd be different at any other jurisdiction within the US.
Indeed. Luckily at least some people in power still care about quality for their citizens. Some places may not be able to afford the lawyers in spite of wanting to do the right thing, so I'm not sure what happens then.