Garbage bin on Khao San Road, Bangkok

I was on Khao San Road, Bangkok last night. Everywhere there is street-sold food and drinks.

One thing that amazed me, regardless of all the drunk people, there is almost no litter on the street. Though, I found myself looking for a trashcan all over the place. I found 1 in the whole street. And some of the stalls seem to have a small plastic bag for their own garbage?

So I'm wondering, is there something I missed? Is it okay to use the street stall's garbage bag? Or can we just let our empty beer bottles somewhere on the street and it will be cleaned up by poor people trying to collect a recycle fee? (I've seen this happen in Vietnam years ago)