> so there is little incentive for them to fix this.

This kind of stuff is typically death by a thousand cuts.

Add on that a lot of the places it leads are under roads that will have to be shut down for weeks/months and you start to realize the costs and impact of fixing these leaks are enormous.

If it is a local leak they can fix it in a few hours but most often the whole pipe leaks (or maybe every joint) and so the whole road needs be redone - thus it is worth waiting for the road to wear out.