The current German system is nothing compared to the former East German bottle reuse system. Disclaimer: I grew up in East Germany, and during a summer break when I still was at school I worked in a small local brewery in the bottling facility at various machines for a few weeks, seeing the system in action.
In East Germany we only had very few bottle designs that were used throughout the entire country and all firms filling something in bottles used those designs. You could return a bottle filled with beer in the north of the country by one company and return it in the south and refill it with lemonade.
When I worked in the brewery we had trucks carrying returned glass bottles coming in, several per day. The labels on those bottles did not matter at all, only the form of the bottle did. They were sent through the washing machine, followed by a visual inspection station (today that would be automated, back then somebody had to sit there and watch endless streams of bottles pass in front of a bright white light source).
New bottles were fed into this system maybe 5% of the total nr. of bottles, maximum. The bulk of the bottles we filled had just been collected from all other the "Kreis" (county) that or the previous day.
There was slightly more variety for bottles with spirits, but non-alcoholic beverages and beer all had a handful of generic designs only:
- https://i.pinimg.com/originals/8a/2a/16/8a2a16b9573f33af14e1...
- https://www.picclickimg.com/d/l400/pict/283478094305_/DDR-Fl...
- https://i.ebayimg.com/images/g/TdAAAOSwy6hc0vzC/s-l400.jpg
- https://i.ebayimg.com/00/s/MTYwMFgxNjAw/z/01kAAOSwoptdW8pU/$...
The current German system has all kinds of bottles and LOTS of restrictions. The labels have to match, I cannot return bottles unless the shop sells these exact bottles (including the brand). There were no restrictions in the GDR and only very few designs to deal with. There also were no plastic bottles and cans, or if we had any they were too few for me to even remember. Sure, that last one is confounded by time, there were not that many in the West in the 1980s either.