I donate to people, but is forcing (violently if necessary) other people to do the same ethical? Aren't there better ways?
The charities people give to? For the most part, it's acute and visible charities. Very few people give to the same charity again and again, over the course of decades. People also give to attractive charities - kids with terminal diseases is a much easier charity to raise money for than mental health in young adults. Same with animals - people care about cruelty to dogs, but they don't care about cruelty to voles. And while you haven't said it, another libertarian refrain is that people would donate more than they get taxed, which is obvious nonsense, because nothing is stopping them from disposing of that extra money.
Anyway, if you don't want "violent" (stupid bloody redefining, that) taxes, then move to Vanuatu. It has good weather, happy people, a small government, and the army is so small it's also the police force (fewer than a thousand people). There's no income tax. Of course, there's little comparable in the way of infrastructure or services, but you'll get to live the libertarian dream of hiring your own garbage collector instead of having one violently forced on you by the incompetant apparatus of the overbearing state.
This. Libertarians live in some sort of idealistic fantasy, where most humans are intrinsically good, and inclined to do good, like help the poor and needy around them. That is emphatically not the nature of the average human. We absolutely need to force and coerce people to do good, under the threat of violence (for non-payment of taxes).
(By the way, I don't think most people would give more if not taxed, at least all else being equal, but not because they're "not good". There are many incentives at play.)
If democracy is the rule of majority and the majority of people are "not good", then you're ruled by people who are "not good".
If government enforced people to do "good" (not smoke marijuana, preventing gay people from reproducing, allowed building with asbestos), and then the changed their mind (allowed to smoke marijuana, allowed gay people are to reproduce, banned asbestos), did they enforce the "good"?
Moral objection to spending is what what the defunding of Planned Parenthood and the boycotts of Chik-Fil-A are about. I don't think there will be controversy around treating suffering people, though.
Which is both sad and hilarious, since only 3 percent of the services provided by Planned Parenthood are abortions, yet they provide an overwhelming amount of non-abortion services to women across the country.
And there's moral objection. To paying for health services for women who can't afford it.
http://www.npr.org/sections/itsallpolitics/2015/08/05/429641...
In a democracy taxes would be considered ethical, by most. Even for redistribution.
> Aren't there better ways?
There could be. Do you know any? Use your vote.
People are better off spending their own money in the sense that they get to choose how their money is spent – but their lack of competence/expertise can for instance make them make bad choices (as in choices that don't lead to the desired goal), and resources will thus not be better spent.
Don't get me wrong, though – it's not like politicians are experts either.
Things are seldom as simple as ideological hardliners claim that they are.