Well, my original example assumed that there was no state and no taxes. Only private enterprise and only Bitcoin.
I was trying to prove that people might still build bridges and roads in smaller towns, even if there was no "third party" to pay for them and even if there wasn't enough traffic over the bridge to pay for the bridge. Bridges to small towns are hugely beneficial to those towns, so the people in those towns will just have to pony up the dough and pay for it, themselves, or deal with having no bridge.
But it was like, just take out a loan. Why would I take out a loan for something like that? I'd pay double for it, in the end, and be tied to the debt.
But the counterargument is that, otherwise, people willing to be benefactors of a bridge would own the bridge, through the building society. So, rich people would pay for many/most of the public infrastructure and businesses, and everyone else would depend upon their largess. Whereas, if one person could just go get a loan from a bank, he would be the person owning the bridge in the end, after all, it was his idea. And then everyone in the town would bleed tolls out of the nose or take the ferry or build a second "town bridge".
But the bridge probably still remains unprofitable, so the benefactor is now the rich financier lending for mysterious reasons, rather than the rich building society people who just wanted a bridge to drive over themselves, and there is a builder trying to pay back 100 BTC for a bridge (no more discounts and volunteers, after all). How is that better?