Voting requires the voter to make decisions, hard decisions. Even decisions about other people's money. Sometimes the status quo is unbearable and something has to be done. Where exactly is the unfairness in taxing wealthier people at the same percentage as middle class and others? I'm pro capitalism, but the argument that capital gains taxes need to be lower than income is a separate argument. There are probably great reasons for capital gains taxes to be much lower than income, but fairness isn't one of those reasons.
1. Volunteerism doesn't scale.
2. Charity doesn't support everything. I've done non-profit fundraising and rich people like to give money to put their names on buildings a lot more than they like to fund operating expenses in local charities.
3. People like roads and bridges and such, but a lot of services require people and salaries and it's much harder to raise money for things like that.
It's not immoral to vote for taxes. People vote for taxes that they pay and they vote for taxes that they'll never pay, but when individuals in the government don't act, the responsibility to do the difficult lies with the voters.