We agree there are “social goods” which require a collective effort to complete (like roads, hospitals, infrastructure, etc). If not, we must have a different conversation before this one, probably about the issues surrounding anarchism/libertarianism. It doesn’t matter what in particular needs this effort, simply that there is something is enough. We must then form a body to collect resources, in a fair way, from everyone. That’s taxes.
We vote in a flawed, yet democratic way, to decide how that money is spent. Even in the most idyllic of democracies, people will have a portion of their money spent on things they disagree with. Accepting compromise is a necessity of any democracy. That doesn’t mean we’re completely stuck with this situation, there’s a partial solution.
The government allows you to choose which social good your money goes to but then charges you a premium. You agree to put more money into society in exchange for having some control over its usage. This is charitable donations. The idea is that all charities perform a similar social good as the government. Many focus on alleviating the effects of poverty on specific groups, tending to the sick/injured, dealing with disasters, or foreign aid. These are all things the government would have to do if a charity didn’t. A tax deduction on donations allow you to claim a percentage of your donation. You have diverted some of the money that would have gone to the collective pool into your chosen social program. So long as it’s always just a deduction based on a fraction of your donation, you’ll be paying more money into the ‘social good’ then you would have with straight taxes. Additionally, the government can encourage certain charities by modifying what that percentage is based on the type of charity.
This is also why voting is important, regardless of your political affiliation. Your money is being spent by people and you really should try to influence how it’s used. Whether you believe in starkly honest voting or strategic voting, you definitely can’t sway the usage of those funds by not voting.
I’m well aware donations can be gamed by the rich/corporations to reduce their taxes. False charities and loopholes allow abuse. This isn’t a flaw with the idea itself, merely a facet of any human created system. There are always cracks in the machine.