I also keep a trash can in my car and empty itaybe monthly (I mainly throw away crushed plastic water bottles and napkins).

I started doing this when I realized nearly every public trash can at any fast food/breakfast/coffee shop/gas station was overflowing.

This builds a culture of IDGAF and people litter. Begs the question that part of the core issue is standardized reusable cups (8oz, 12oz, 16oz) maybe with a credit like $0.05 every time you use it? It would require a cup washing station.

I think most coffee shops would use your tumbler but idk what the process for cleaning it during your several coffee refills throughout the day.