A) I see. No I'd never take that position.
B) Would I donate? If I could and if I feel the organization is deserving, as I do now. Could I donate more if I wasn't being taxed so much? Yes. I don't believe in mandatory services because I don't believe in slavery, so I wouldn't be ok with such a thing.
Just in regard to the "shit getting done" part, consider...
http://philanthropy.com/article/Donations-to-Aid-Haiti-Exce/63756/http://www.forbes.com/sites/dandiamond/2014/08/29/the-als-ice-bucket-challenge-has-raised-100m-but-its-finally-cooling-off/These are random, and a drop in the bucket, truthfully, but such showings suggest shit does actually get done when necessary. Keep in mind this is on top of being quite burdened with high taxation for the social services of health, education, public safety, etc.
I think we've sort of been conditioned to shift our faith in humanity to faith in government, unfortunately. Though it's quite obvious they make up a subsection of humanity so they're clearly subject to the same deficit of caring the rest of humanity (seemingly) possesses, for some reason they seem to be held to a higher degree of respect or belief that they will do the right thing(s) when laymen won't.
You previously mentioned volunteerism for something that's ridiculously hard work that requires trained individuals to do. I don't know about you, but my training for putting out fires involves "dump some fucking water on it?! I dunno!"
Donations to pay trained people would be better in the sense of we don't have a ton of people doing shit they have no clue how to do. But aren't donations kind of like treating taxes as "pay what you like?" What if under the donation system, someone decides "eh I won't donate, fuck 'em, someone else will pick up some slack!" What if a whole lot of people do that? Who's freeloading now? Now you've got some suckers, excuse me, "donators," picking up the slack for everyone who doesn't give a fuck to do so.
For that matter, how can you say donation campaigns are "random and a drop in the bucket," then say "shit does actually get done." with a straight face? Not to mention charities can be more wasteful than governments, and most people don't spend the time to educate themselves on how much money they're donating is actually getting put to use for the thing they're trying to support, instead of getting shuttled to advertisement and administration. How's that for faith in humanity? Charity, like recycling, is a nice way to say "I did good" when you didn't actually do much of anything.
I have faith in neither humanity nor government. But I've read plenty of stories of what happens when a government collapses, and let's just say those people really got to see just how little you can trust your fellow man. You don't have friends? Well guess what, now you don't have supplies or food, either, because the people with friends just came and took it all away from you to support themselves. In that world, it's join or die.
In the taxed world of government, it's join or die (read: pay taxes or get arrested), too, I understand that. But at least in this instance, my toilet flushes when I take a shit in it, and I don't have to steal my food. That alone is worth the tax fee to me.