And so defining the level of work required in law is usually not going to help anyone. This is why unions exist - so the people that know the workplace and subject matter best can negotiate to make the job fair.
... which is the ridiculous thing. As much as unions do have problems, I think a better fix to all of this would be a law that just said "all warehouse employees must be a member of an independent labor union". Amazon has fought tooth and nail to keep their warehouse workers out of unions.
(I don't love this sort of law, but it'll probably give these workers a better outcome than they have now, and likely a better outcome than the law that we're talking about here.)