Physical labor, sure, multitasking is hard. Otherwise, not so much and the excuse of “can’t multitask well” is just that, an excuse for incompetence.
So would you define driving and texting as “physical labor”? What would qualify as multitasking under your definition? Singing and playing an instrument at the same time maybe, or is that “physical labor”?
In my view singing and playing, even though I don’t do either, are two aspects of one task. Off hand I can’t think of a time I have seen anyone actually do two tasks at the same time, they switch back and forth. That is why studies show that even driving while talking with a hands free phone is dangerous because people cannot focus on both things at once. There are people who can do a fine job of painting a portrait or sculpting a statue, show me one who can do both at the same time and I might begin to believe in multitasking as something other than a misused word.