Any conduit not pulled and sealed within a year or two of laying will be worthless. You typically need a junction/pull box about every 1000'. At each of these access points each conduit needs to be sealed off but very rarely are because the guys pulling the conduits expect the guy pulling the cable through will do it. Even if you seal them up you've still got the issue that because you didn't pull a line through it right when you laid the conduit you don't know if the conduit's got to much variation that will prohibit a pull (you cannot lay this stuff perfectly level and straight, you end up with it going up and down and side to side and if it has too much of that you won't be able to pull a cable due to the friction).
When you pull the cable during construction you can verify and fix the conduit before you install the asphalt and close it all up. If you wait you have no idea if the conduit is good until someone tries to pull a cable. Rat's or other rodents will build nests, they'll fill with water and sand, etc, etc, etc. After about 3 years without any cable being pulled you won't be able to get a cable through them and the conduit you installed is worthless. It's far better for cities/counties/states to plan these networks out and use them themselves for traffic operation. Locally our DOT puts in 4 or more conduits every time they lay them for their traffic network and the DOT typically only uses 1 or 2 of them. They then rent the extra conduits to companies. Because the DOT pulled a cable through the conduits during installation and the conduits are in a duct arrangement they know the other conduits are good. In addition because they pulled they also sealed up all the other conduits so critters and debris can't plug the conduit.
I support what the congress critter wants to do but a blanket requirement to install conduits is just dumb, the locals need to be involved and supporting the installation. Forcing a DOT or city to install conduit they themselves won't use is just a plain waste of money,