How come? What would legally stop the city from walking away?Contracting out garbage probably would have happened regardless of who won this election (maybe not Joe) - it's an inevitable part of things.
Completely removing public sector unions is almost impossible, though. Certainly at the city level, there's not a lot of power. Provincially a lot more could be done, as they could reform the arbitration system so that unions don't actively try to force legislation that will get them in front of an arbitrator.
I think unions are important but public sector unions are challenging. With the private sector, there's a built-in incentive for the union and management to work together and compromise. If a car company is facing bankruptcy, the union will make concessions to ensure things stay afloat. In the public sector, the union doesn't necessarily have that motivation - the government has, essentially, a limitless supply of money for wages and can't go bankrupt.
It's an unworkable model and a challenging one. Anyone who purports to have easy answers related to these issues is lying to you.