The US doesn't use that much glass compared to aluminum and plastic. Aluminum recycling is very efficient which is why recycling centers really want it and refilling aluminum cans doesn't work well compared to glass because they deform and crumple a lot. Recycling aluminum takes about 5% of the energy of creating new aluminum.

By removing aluminum cans from curbside recycling, they're just adding additional steps and labor to recycling the cans.

Looking into the German system, it's really just glass bottles that can be refilled. Glass bottles are pretty uncommon in the US except for beer (and even with beer, I find cans way more common). You're definitely right that recycling centers aren't looking for glass (probably because it's energy intensive), but they are really looking for aluminum (because it's so easy to recycle).

The number of re-used bottles is down 30% in Germany in the decade after the bottle deposit scheme was created in Germany. Almost all bottles are getting returned (97-99%), but stores have been moving away from refillable glass bottles.

Yep, cleaning and refilling is great for glass, but glass is pretty uncommon in the US. Their use is steadily declining in Germany too and less than half are re-usable today. That might mean that it still makes sense to run this in Germany, but does it make sense to have a deposit for non-reusable bottles?

Whether an aluminum can goes into curbside recycling or is returned to a store for a deposit doesn't make much of a difference - it's going to be made into recycled aluminum. A glass bottle might be simply cleaned and refilled. So, we don't care where an aluminum can goes as long as it's recycled. We do care that a glass bottle is returned. So it makes sense to maybe put a 15 cent deposit on the glass bottle that can be redeemed while it might make sense to simply put a 5 cent tax on the aluminum can which you can't get back.

But some of this is culturally relative. Some places have big problems with people littering bottles and cans. A bottle deposit means that people won't just throw the bottle on the ground - or if they do, someone else will collect it for the deposit. The Irish plastic bag fee helps the environment because it got people to stop using so many plastic bags, but one of the most visible differences is the lack of plastic bag litter all over town.

Given Germany's high level of re-usable bottles, the return scheme probably makes more sense there. Articles also indicate that there may have been problems with bottle litter of non-reusable bottles and the deposit gives people an incentive to redeem the bottles (even if they're collected by Pfandsammler rather than the original owner). However, given the US' low rate of refillable glass, it seems to make less sense here. At least in my area of the States, it's illegal to drink alcohol in public and soda is the only other item with a bottle deposit. Seltzer, sports drinks, bottled water, etc. don't have a deposit. Still, we don't have a lot of cans and bottles becoming litter so we aren't as worried about that. As such, it seems more worthwhile to have the aluminum recycled efficiently via curbside pickup rather than individual transported, counted, etc. just to end up with the same fate.