What? Entire Europe uses debit cards without basically any issues. Some people are really afraid of their own shadows...
USA seriously needs to move on with the modern payments cause discussions like this are both ridiculous and embarrassing to read in 2024.
Theoretically there are differences in how fraud is handled between debit and credit cards here (though in practice you get your money back regardless). Combined with the fact that PIN isn't mandatory even for debit card purchases, I can see why people wouldn't want to bother risking it if they're able to use an alternative.