I can tell you you're absolutely wrong about the average person. I live in a place with no public infrastructure (I'm talking about, not even public roads, and not some rich HOA, a ~poor unorganized community without any infrastructure association) which has allowed me to view how average people react when there is no taxation based infrastructure. When it breaks, the neighbors help. I help maintain the roads for my poor neighbor. My other neighbor helped fix my water line when it broke. Sometimes I take my heavy equipment and donate labor to prepare for storms, etc. The infrastructure is literally donation based. We get it done for a tiny fraction of what the tax based system cost and everyone is far better off, even if the amount donated is less than what the taxes would be and some people "cheat" the system.

It's actually quite rare to find someone who says I will help the poor, but only if my neighbor also pays, otherwise they can get fucked. This is very bizarre thinking. The people in my basically ancap-dystopia neighborhood don't even behave in this sadistic way. It honestly sounds more like a manufactured "gotcha" to win an argument than a way someone would think.

In reality the fraction people that would vote to tax themselves, are more than willing to donate in the case they don't get the tax, your sadistic MAD view where you punish the poor just because some other guy didn't help too is relatively rare and not indicative of the mindset of most people who are voting to help the poor. I honestly think that most anyone who would vote for the tax, does not act that way when dropped in a neighborhood like mine, and you probably would not either.