First of all, thank you for starting this thread to prevent any ongoing hijacks in the other one. Some of these points (of which this is just one) seem to have arisen from my comments in the other thread.
Your quoted context here is incomplete, though. In the context of the garbage strike, it wasn’t only about freelance garbage removers being beaten up. It was also about private citizens, seeking sanitation in the face of the garbage strike, attempting to deliver their own garbage to the transfer stations, and effectively being denied access by union thugs.
To be fair, access wasn’t totally denied, but it amounted to the same thing – it was more a matter of very, very significant intentional delays, to maximize inconvenience to the point that many people either gave up or got into confrontations with the picketers, or just threw their garbage into nearby fields, the end result being the same – that sanitation and health in the entire city was at risk.
Sometimes, sure. But my garbage strike example may be illuminating. Recall my comment above about citizens just trying to properly dispose of their garbage during the strike and sometimes getting into confrontations with the strikers. Police were sometimes on site. So now they’re making judgment calls – “I just want to take my garbage to the landfill” … “No, you don’t – that’s our job and we’re on strike”.
Well, around here, anyway, police have very strong unions (as does apparently every other public employee). Who do you think the police were most likely to side with in these sorts of discretionary confrontations? Yeah! Cross-union solidarity FTW! 
That doesn’t meaningfully distinguish between “inconvenient” and “dangerous”, as in my garbage-strike example above. The other key point here is that the union was not only withdrawing the services that their members provide, they were also explicitly preventing individuals from doing those things themselves.
Sure. The problem – around here, anyway – is that in our liberal social democracy governments cave all too readily to public union demands, and have now created monsters that are virtually unstoppable – the masters of all they survey. We have cashiers at government liquor stores making more than research scientists, and garbage collectors able to hold citizens hostage to dangerous filth in hot summer heat.
I’m totally with you here, my friend. You’re trying to do a good job in a state with shitty politics and a shitty government, and all the power to you for what you do. You need unions. That doesn’t change my other arguments in other contexts, though.