From what I understand by reading around (I'm not from the US) petty theft in some areas causes already the problem you're mentioning for offline businesses as well.
I wonder why they keep those stores open sometimes.
I used to live in SF and would see shoplifting all the time but now live in NYC and haven’t seen it that much.
I never worked retail myself, but I've heard plenty of stories from people who do.
One person I knew called it "taking out the trash". They would fill trash bags with cds. He had a room full of unopened ones.