During my years in retail exactly one customer ever had a problem with me saying "no problem". He also said he was an assassin. That's not a joke. This old, fat boomer said I shouldn't say 'no problem' because some people might take it to mean 'yes problem' and then told me he kills people for a living.

That's the stability of people that can't understand the meaning of words. If I go to a police station and say I am a serial killer vs I'm not a serial killer, I don't expect them to react the same...