I personally think unions would be unnecessary if the government did it's job in protecting worker's rights. Unfortunately they usually don't, making unions still necessary.
And the only government employees "bringing government down" is the elected politicians who make the rules. Most government employees I know are just regular hard workers trying to do their job. Heck, I'm a (state) government employee and I'm hard at work right now
I think it's a straw man to say union= shitty workers. Yes, there may be a problem with shitty workers. Ok, but why does that mean unions are unnecessary? If they are protecting workers at all costs, then maybe. So don't protect workers at all costs. But most unions I've been a part of do things like negotiate overall salaries, make sure we have benefits, provide a place to go for workers who might be unfairly treated, etc . I've been fired from a unionized job when I was a shitty worker, and the union didn't intervene in any way, so where does all this stuff about unions protecting shitty workers come from?
The other argument is "everyone else has a crappy job, why should union jobs get better wages and benefits?" I think the answer to that is that we need more unionization, not less. Yeah in a 'free market' you can find people who will work for lower and lower wages. But what does that mean for our society as a whole? It means fewer and fewer jobs that pay at the level in which the workers can support their family, and lots of people working for minimum wage- which is not enough to live on. Yeah "get a better job" ok, but someone needs to do all the crappy jobs in society- it's not like we can have a society in which EVERYONE has the better paying jobs requiring a college degree, or else our buildings wouldn't be clean, we wouldn't be able to order our crappy mcdonalds breakfast, we wouldn't have people to wipe our asses in the hospital, etc. So yeah, some people can get better jobs, but our society as a whole needs people to do the crap work in order for society to run. So why not appreciate those people by paying them a wage that they can actually afford to live on? If the government would step in and say "yeah, let's do that" we wouldn't have a problem. But they're not doing that. Hence the need for unions.