But unskilled union labor dictates that it has to be them or those whom they approve of "around to do the actual work" ("actual" is doing a lot of heavy lifting here) or else the business that they don't own can't be a business at all.
It can't be anyone else, even when it could easily be.
Businesses that employ unskilled labor aren't the equal partnership that you want to make them out to be.
See the fact that the trend is toward international outsourcing. Unionization will increase that trend, even if the cashier that the public sees is now making $20/hr (now at half-time hours and much of her family has now had to move out of the area to find work, due to a downward trend in job availability: aggravating the gentrification or the depopulation trend, depending on the area).
I think that Unions are economically and socially useful, but not in the case of what is essentially unskilled labor.
As beyond the rational nonsense of such a proposition, the existence of non-unionized unskilled labor plays an important economic and social role. For one, these jobs maximize job availability to a lower class that is growing for reasons other than job availability and average salary trends. The alternative being unemployment.
And unskilled unions should especially be discouraged when other wage control issues are both not addressed and frankly aggravated by the generally pro union side.
In summary, unskilled labor wages should be buoyed by measures other than unions: reasonable minimum wage law, labor supply control at the population level, etc. As unskilled Unions otherwise distort the economy and social sphere too much. Last, one can't rationally justify the existence of such Unions on profit margin. If they are justified for one, then they are justified for all. And vice versa.