I can't say much about pre-78. The PB pipe became popular because it was inexpensive and came in a roll, so it was easy (and cheap) to install. Prior to that there was galvanized steel, Black PVC,  and copper. Today, they use Black Poly (PEX). The underground water line can be seen in the crawl space where it connects to the house plumbing.

When it comes to "fix it right the first time", the county may be penny wise and pound foolish. The county guys have told me that there is not enough money in the budget to do it right. Patching is cheaper than replacing. I've seen them repair a break in less than two hours, sometimes without even cutting the roadway, but a line replacement takes at least 4 hours and perhaps a large pavement cut. They cut each end of the pipe and pull the new pipe through the old using an attaching fixture that splits the old pipe as the new comes thru.

As a dog walker and biker, I have called in at least ten leaks I have spotted. The county sends out someone to verify within the hour, who then calls for utility markings. As soon as the site has been marked, they are there to fix it. I've seen the whole process take less than six hours.