But, again, you're assuming that, if the people who drive over the road won't pay high tolls, then it's a poor use of resources.
But the people building the bridge do not think it's a poor use of resources, that's why they want to pay themselves, to have it built.

Using resources well doesn't always require someone else's willingness to pay me money to do something. Nobody has to be willing to lend me Money to eat a sandwich and I don't need to charge people to watch me eat it, for it to be worth eating. I'm hungry. I want a sandwich. I lose the money on the sandwich, but that is okay because I'd rather lose the money on a sandwich than stay hungry or eat plain bread.

Do I need to prove that a house or a car is worthy of a loan? No, I can just save up money and spend it, building a house or driving a car.

Once you look around, you will see that most things that currently receive loans will no longer receive them. Or so I thought. 🤷‍♀️ 

 Almost everything done is for consumption or common use, and not for profit. 

 Even a lot of businesses only exist because the person who owns them or the people who financially back it want it to exist. There is no expectation that the business will turn a profit, often just that the running costs are covered. People just want to have a nice gathering place in the town, a small grocer in the village, a relay everyone can write to, or a school canteen with healthy food for the children.