The common 2kg×6 PET bottles format is too heavy for glass bottles, so you end up paying more for heavier 1.5kgx6 bottles that are going to last you less.
IMO it's simply habits
no one would buy beer or wine in a plastic bottle, because it feels wrong (and it is if you ask me).
Here in Italy nobody in their right mind buys tomato sauce in plastic bottles, our granmas would come to haunt us at night if we did.
but we buy water in plastic bottles ¯\_(ツ)_/¯
Where I come from beers come almost exclusively in glass bottles for the large ones (66cl), aluminum cans are only used for the small ones (33cl) but you can buy them in glass as well.
There is usually no price difference whatsoever
For example
https://www.amazon.it/Peroni-Italiano-Moderatamente-Gradazio...
https://www.amazon.it/Peroni-175-Anniversario-Birra-Cassa-dp...
Many of the cheapest beers are imports, for example Bavaria, that you usually find in aluminum cans in Holland but in glass bottles in Italy.
I can't explain why, but for us some things must be bottled in glass or they aren't "good".
Tomatoes is another example: you can find cans of tomato pulp or peeled tomatoes, but not the sauce, it always comes in glass bottles (it exists of course, but it's a very weird choice to us).