I sympathize with the OP on all he says, but what does he mean by this, aren't these expressions synonymous, the only difference being the tone?:
> although saying “my bad” when you mean “my mistake” comes close
...and going further on the linguistic ambiguity route, most people saying "can't do" actually mean simply "I hate it / I'm not good at it, and because it's so much effort for met o do it I'd rather not have to do it"... and the only bad thing in it is the uberannoying implied "I don't want to learn it, don't try and teach it to me"...
'My bad' is a foolish thing to get upset about people saying. People have said it for thousands of years and they're going to keep saying it. See: "Mea Culpa"
> although saying “my bad” when you mean “my mistake” comes close
...and going further on the linguistic ambiguity route, most people saying "can't do" actually mean simply "I hate it / I'm not good at it, and because it's so much effort for met o do it I'd rather not have to do it"... and the only bad thing in it is the uberannoying implied "I don't want to learn it, don't try and teach it to me"...