Re: Tax avoidance costs
That doesn't work. You can't base a system around voluntary taxation, because it gives a strong competitive advantage to non-volunteers. Such a system is inherently unstable. Taxation must be as evenly spread as possible (for some vaguely reasonable definition of "even"); a voluntary basis is the opposite of that.
These people who protest, I'd wager the reason they protest is because they understand the above perfectly. So, no, volunteering money would be against the ideals they're pushing.