I've heard that Singapore manages to do it. Copy whatever they do. It doesn't need to be 100% effective, because it's easy to rip the caps off the new bottles making them not 100% effective either.

cane people you find littering, like they do in Singapore.

This is not true. You will not get caned for littering in Singapore. You might get a fine, or be sentenced to clean a public area while wearing a bright uniform (so that everyone can see that you're being punished). See: https://www.nea.gov.sg/media/news/news/index/nea-increases-v...