[gumby]

Sure it does, for the cash flow reason I mentioned. Consider the debt payments as an insurance premium against financial problems.

A municipality can take on debt for a capital expenditure on a bridge or something that might reasonably be dismantled or replaced around the time the bond is paid off, for the same reason.

I would not consider either case to be irresponsible or economically irrational in principle. Especially as humans have finite life spans.

[clairity]

sure, a bridge provides net economic benefit, so is not simply a depreciating asset. it's paying for broad benefits that accrue widely across society, rather than strictly to the government (externalized benefits). that doesn't happen with cars. in fact, cars produce large negative externalities. there's also fewer viable, affordable substitutes for bridges, whereas cars have multiple viable such alternatives, which makes debt often a bad choice for cars but not bridges.

but to the point of bonds, a lot of bond measures are not for net economic benefit, but rather political gain (school funding bonds, for example, tend to fail to improve educational outcomes despite the political rhetoric).