I think that may be a fair critique, as long as there's a better alternative to use. If the distinction is between someone that has done extensive training or preparation for a job, to the point that it requires months or years of experience doing that job or being trained specifically for it, and to a job that essentially anyone can do and they just need a day or so of on-the-job training (if that), what's the better terminology to use?

I acknowledge there's a full spectrum between they points (e.g. painting, where anyone can do it, but professional painters have many skills developed over years to make them both more efficient and with a better outcome).

Perhaps the problem with the label is that it's being attributed incorrectly? I don't think it's saying the person is unskilled in general, just that the person is unskilled in this job. There are plenty of instances where people that are skilled in one area but unable to find work in that area get a job in another area they are unskilled in to make ends meet, and I think those jobs are generally for unskilled labor. In those cases, they likely are unskilled in the job being done.

Amazon also encourages some of this. Recent radio ads in this region include, as close to word for word as possible.

"We are now hiring for X. [Insert some pay, benefit information here]. Apply online. No interview required. Start tomorrow/this week."

At that point, you really are looking at 'unskilled' or at least 'not specifically skilled'.

If there is no difference in compensation for skilled and unskilled work, why would people invest in becoming skilled?

There are other factors such as confort, safety, schedule flexibility, interesting work, etc.

It's useful. My first few jobs were unskilled labor. Janitorial, food service, department stores. Just getting the job done requires next to no training and certainly no prior experience.

It's difficult to push for higher wages or better working conditions when your productivity after 5 years is only 5% more than someone that started a month ago, but that's reality for unskilled work.