As to whether those wear marks on glass beer bottles are from them touching together during transport I'd suggest that this actually is not the case. They shouldn't come into contact with another, seeing as they are transported in crates with pockets for individual bottles. It is far more likely that those marks come from handling in the bottle washing-, filling- and labelling machines where the bottles gang and rub against each other. If you're from Germany you might have watched 'die Sendung mit der Maus' ('the program with the mouse', a long-running television program aimed at children which amongst others details all sorts of industrial processes) where this process is followed from start to finish. Here's an example from the '70s:
I'm drinking from thick reusable/reused plastic bottle everyday here in Berlin, even coke is sold in them, they still exists
> it ended up being more expensive to clean these plastic bottles
Which is a shame because what we save in $s now will cost us much more than $s in the future.
> It is far more likely that those marks come from handling in the bottle washing-, filling- and labelling machines where the bottles gang and rub against each other.
Could be, either way it's a sign they are indeed reused. Thanks for the link.