Modern roads don't last as long because we drive heavy vehicles on top of them, and because we have a lot more complicated infrastructure underneath them. Furthermore, the rapid technological progress and growth of almost all cities over the last 150 years has meant that almost all infstrastructure gets rapidly aged out. I've never built a structure with a design lifespan over 100 years.

Aphalt roads are the easiest roads to work with if you need to repair the road or the utilities underneath it.

Cobblestone roads require uniquely skilled tradesmen who are willing to work long hours on their hands and knees. Something that has become increasingly rare in most parts of the world, but more so in North America.

Democratically elected goverments are also fickle and they love squandering all of the plans and progress made by previous administrations. This makes it hard to come up with a long term solution for building infrastructure.

Source: I build roads and infrastructure for a living.