I make a practice ALWAYS to ask for plastic at the paper-please (hippie) friendly stores out here in Los Angeles. And I refuse to be shamed.
Molon labe. Must take a stand.
I do, too, and explain that I am not a Tree Murderer.
The clerks usually think for a moment.
If they think for more than a moment, they get a look in their eyes that says, "This program has performed an illegal function, and will be shut down."