There are two primary types of plastic I want to talk about, pex and poly B. I was like you once and was concerned that plastic pipe was not going to be as good as copper. I soldered a lot of pipe over the years because I was afraid of change. About 7 years ago I renovated a home and re-plumbed the entire home with pex piping. I was amazed at how easy it was to work with. The invention of a good form of plastic pipe didn’t come all at once, however. Initially a gray pipe called poly “B” was made with plastic fittings that turned out to be a disaster. Thousands of homes were flooded in the early years when poly “B” was first introduced. The problem was the stability of the poly butylene itself. The pipe had a tendency to change size and when coupled with plastic fittings it was common for the pipes to blow apart. Changes were made and copper and brass fittings were introduced that solved this issue. Today’ pex appears to be very stable and is far better than copper piping in my opinion.