Glass chips and breaks. "Tupperware" can take punishment for years. Decades even. Our household started replacing plastic containers with glass last year and we've already cracked 3 and smashed 1. The plastics, used for pet food now, are unchanged.
Strange, I rarely break any of mine, and even when I do, I just replace it
Cost and weight, most people won't see the plastic version as something important and won't invest. Also the weight difference means transport to stores cost orders of magnitude more than the plastic so its more difficult to stock.
Likely plastic was cheaper, easier to transport and easier disposed