"In 1975, 94% of milk in the UK was in glass bottles, but as of 2012 this number was down to 4%."
The reality is that plastic is so much cheaper that people balk at the cost of recycling exactly like the price of humanely treated chicken eggs even if they want to do the right thing.
> balk at the cost of recycling exactly like the price of humanely treated chicken eggs even if they want to do the right thing
That is right before they balk at paying the farmer more than 25p a litre to produce the milk they are going to drink.
Norway and other countries have a deposit system where you pay extra per bottle, and then get the money back when you return them. Places that sell these products are required to accept any bottle that their customers bring them, so most of them want to use these automatic machines to avoid hiring extra staff.
https://www.youtube.com/watch?v=ZI7OldXuq7c
These machines have existed since the 70s, but the modern machines are of course much more intelligent than the early models. They used to accept glass bottles too, but they are not part of this system anymore. (glass is recycled separately)
Tomra is one of the larger manufacturers: