Here (Finland) it is actually illegal to use any container that is similar that one used for food or drink for storing chemicals. The reason is that someone could accidentally drink chemical as the container looks familiar - like coke bottle..
Despite of that, a lot of people use PET bottles (lemonade, soda) for storing chemicals. Including me, because those bottles are easy to get and they're flexible enough for squeezing all air off.
I would not return these bottles for recycling, even though they're crushed and melted.
But you never know what is kept in the glass bottles that are returned for reuse. Or what was kept on the PET bottles when they were still returned for reuse instead of crushing.
Someone could return a bottles used for storing gasoline, rat poison or some other toxic stuff..