crypto isn't actually that great for finance but it could solve all public goods coordination
in general, markets have historically been great at pricing what a single person or a centralized firm is willing to pay at any given time for a specific good/service
markets have been bad at pricing what a decentralized group of people/firms are willing to collectively pay at any given time for a specific good/service
but if we could find a way to price that collective desire, it would be very interesting, no? and potentially solve many problems?
like for your bridge example, you say you don't think about the bridge maintenance until the bridge has collapsed, but I think you're more altruistic than that
if there was a sign at the front of the bridge that said "deposit funds here to upgrade the bridge" and you knew you could chip in a dollar or two to help the cause, I think you would do it
especially if you could reasonably trust that:
a) you gained reputation within your community for doing so
b) you knew these sorts of deposit boxes had worked well in the past for speeding up bridge repairs
c) you would gain some sort of governance rights over deciding whether or not the bridge upgrade fund was paid out to a worthy contractor
d) you could withdraw your money at any time before the money was paid out if you needed to
now, in the physical world, it's basically impossible to enforce all of those factors
but we can do it in the digital world with smart contracts and Ethereum
there's even evidence of this altruism happening already in local governance (see screenshot), but it doesn't have the guarantees of factors a, c, and d above because it's managed by centralized city governments
if we figure out how to run these action markets in a frictionless, decentralized manner, we're talking about a service that almost every type of community could benefit from