This is trying to ride a thin line and I don't think it hits the mark. Sure, there are skills involved in any labor. But "unskilled" is just shorthand for not having particular requirements that are rare enough that labor gets to charge more for them. It's not a myth that there are jobs where a large enough group of people can do the job and it pulls down the price you can charge for your labor when you are doing the job.
If anything this is an argument for a higher minimum wage, not a union.
It's a distinction between "on-the-job training will suffice" and "no chance without years of prep."
No shit anything worth paying a human for involves human skills. But some jobs are open to just about anyone who can put up with it, and some jobs kill people when you try to muscle through on sticktoitiveness. A fast food restaurant can bring some rando up-to-speed in a couple weeks. An ER cannot. The distinction is necessary.
Nitpicking the label misses the point:
All labor deserves a living wage.
It doesn't fucking matter how difficult or complex a job is. If your business wants people's time - you had better fucking pay them enough to be there next month. Otherwise, you don't get to be a business.
Surely farming and construction aren't considered unskilled labor? It looks like the left middle square is at a sewing machine which I also wouldn't consider unskilled
Unless you control supply, then you can create artificial scarcity.
There's also the common way where large corporations kill smaller companies or local businesses by predatory pricing techniques, then when those are under, they absorb the business and hike prices.
As manual labour goes, if your market is controlled by a single entity, then even if there's large demand for you, you won't have a chance in getting good conditions.
The same goes if you're a contractor or a small company where your client controls the market.