I think a possible alternative is they’re not a native/regular speaker?
WTF is up with your personal attack there? That's uncalled for. :(
And note, unlike your behaviour, I didn't call you names. I just pointed out your wording was weird. That's not a personal attack.
I've seen the phrase used with medical professionals before.
Never with teachers or other situations though. The results and definition from the duckduckgo search (above) also only show it in use by medical professionals, not with others, and doesn't support your stated meaning.
Sounds like the phrase is used more widely in your part of the world. Good for you I guess. :)
You're making personal attacks as well?
A common theme among many English idioms is that a phrase is found in one discipline (ie. the medical discipline), in this case "bedside manner." Some deeper meaning is extrapolated, in this case it is "showing kind, friendly, and understanding behavior for people in your care." And then the phrase is re-used in other disciplines and contexts where the deeper meaning is what is intended to get across to the recipient hearing that phrase, rather than the literal interpretation (ie. the bed isn't necessarily involved at all.)
As another example: "curiosity killed the cat." There's no cat, and it's not necessary that people will die when this phrase is used. It just means "sometimes following your curiosity leads to bad consequences." Hopefully this lesson has helped you the next time you come across an idiom and wonder why they used that choice of words.