The catch with glass bottles is that they are quite heavy compared to plastic bottles and you have to ship a lot of empty volume around when returning them to be washed and filled.
I remember that there was a brief discussion once that moving the empty glass bottles might be so energy inefficient that using recyclable plastic bottles would make more sense. These kinds of soft plastic bottles are crushed immediately after taken in by the machine and thus take up much less volume on their return trip (fewer trucks with better loads). I unfortunately don't know if this claim was finally determined to be true or false.
The real reason is marketing. Otherwise stores would just have huge tubs of different goods, and you'd fill a standard size bottle/jar, then take the goods away, then bring those standardised containers back and keep doing that until the containers wear out. If you're wealthier, the store would do the washing and refilling.
French supermarkets used to do that with the cheap wine. You used to get "container" or "tub" stores in the 80s (UK) that you could buy loose product and put in your own containers.
This, to me seems a better, more responsible way to do things but it means reducing the numbers of products (only 3 types of extra-virgin olive oil, how will we survive!) and removing marketing opportunities like package labelling and shape. Companies couldn't just reduce the volume of a good in a packet when prices go up nor redesign the label to hide what is [not] inside.
It would be interesting to see how companies would innovate differentiation if, for example, all mobile phones came in a fixed size/shape box that couldn't use mixed media, could only use environmentally friendly dyes in the printing.
I would be generally in favor of reusable packaging for comsumables (not just food, but also soap, detergents, ...). Also, I often stare into supermarket shelves in dismay because some perishable items are sold in fixed container sizes far bigger than what I can comsume before it spoils.
But I don't get why you would have to reduce the variety of product brands to get there. Care to elaborate?
Edit: I have seen repeated news of tub stores opening up in Germany. They are very few and far inbetween, but the the that exist seem to do reasonably well.
Makes sense until you look at the energy intensity of plastic bottle recycling. The most surprising part is discovering the washing stage of recycling is far more intense than for reuse. It's trying to wash and agitate the glue, ink and labels from the outside, not just dried remnants of drink or food.
A truck has to go back to the factory with plastic pellets, and to collect the product, so you're only left with the weight differential. Given the amount of corporate lobbying and marketing pushing away from reuse and towards recycling I think it likely that reuse is the winner in terms of sustainability. Recycling is an externality creation exercise to reduce costs for the business, not overall.
I remember that there was a brief discussion once that moving the empty glass bottles might be so energy inefficient that using recyclable plastic bottles would make more sense. These kinds of soft plastic bottles are crushed immediately after taken in by the machine and thus take up much less volume on their return trip (fewer trucks with better loads). I unfortunately don't know if this claim was finally determined to be true or false.