And private police, private military, private customs & border security... You cannot live in a modern nation and not rely on services that are paid for by taxes.
Why don't the concerned citizens pool their funds together to pay for their own defence?
If we must pay taxes for these things, why must their be so much corruption and fraud (think of the expensive fighter jets and missiles that government agents purchase at inflated prices, from companies that funnel profits to a very select few rich individuals, who funded the campaigns necessary to get the government agents in power?)
There is always an option to unsubscribe from living in a society - it's called "renunciation of citizenship".
Sounds like the purpose of a tax system to me.