Not fair to consumers. Mega Corp created pretty metal cups and we moved off of plastics ones like nalgene. Vacuum sealed metal containers hold ice much better than glass or plastic.
Jokes on us, Mega Corp sprayed plastic liners and/or PFAS onto the metal for longevity. Same with milk cartons. Most of us didn’t know this until years later.
Glass is not an option for people with young children. I don’t want to pick up glass out of their car seat again.
It is not just convenience. It is also cost. How many customers will be willing to pay a $ or more just for the packaging? Every alternative to plastic is much more expensive. For instance, take glass. Glass bottles break very easily during transport and they are also more expensive to purchase. If you are thinking of recycling them, that too adds cost in the process - from pickup, cleaning, drying etc.
The holy grail for packaging would be a transparent, flexible, glass-like substance that is also extremely inert and which doesn't absorb the contents, doesn't spoil, doesn't allow air in or out, retains shape for a long time.... and yet can be decomposed!! As you can see this is a tall order.
Price is king. Everyone knows glass containers are better and consumers prefer them. However, shipping glass containers has a considerably higher cost than plastic from both a weight perspective as well as a fragility/loss perspective. That doesn't even factor in the cost of the glass containers themselves.
If someone invented a glass that was as cheap and light as plastic food suppliers would switch to it in a heartbeat.
What the world needs is glass foam that's strong enough that it won't break while shipping and smooth on both the outside and inside. Think: Glass foam with a Gorilla glass-like surface on both the outside and inside.
Convenience is king, and humans simply aren't really programmed care about long term consequences.