I agree with most of what you are saying but realize that entry level service jobs are just that - entry level so unskilled in nature and therefore less valuable because there is a larger population that can do it (supply and demand) - but all those jobs are highly respectable and provide life lessons, stepping stones, and typically motivation to do better. As for your Dad, an A-tech mechanic can easily make $100k a year but a grease monkey (oil changer/lubber) cannot.
As for the when in the bolded part, I don't know I am sure it aligns with the continued migration to a services economy based on knowledge workers. That said, I think because of that there are specialized labor oriented jobs that can leverage it into higher wages especially if they bring a clean service oriented approach to it.
1. Who defines what an "entry-level" and unskilled job is? Because, back in the 80s - you could for sure define that as baggers at the grocery store, people who worked at McDonald's (except the manager, who was salaried, made barely over minimum wage, and worked 60 hours a week).
These days, it seems like the "line" of what is unskilled has moved upwards AND the percentage of jobs available that are "unskilled" have gone UP. I mean, in the 80s, McDonald's was considered unskilled, but cooking or bartending at a restaurant was not. Now, it seems like the % of jobs available that are in fast food, etc. have gone up AND now we consider cashiers to be unskilled, and salespeople at the Gap to be unskilled. That was not considered to be unskilled when I was younger, believe it or not.
2. My dad has been dead for years, but his top pay was probably $30k per year, which looks like it the equivalent of about $80k today. That's not terribly bad. However, he was 56 when he lost his job and was unable to get another one, due to decreased opportunities and age. (That $30k job became a $12k job.)
Now, for the most part, my blue collar family did not expect to live "high on the hog" on their jobs. They had homes (frequently mobile homes), cars, and cable TV. Nobody really went on vacation, aside from the occasional camping trip. Gardening, hunting were the norm. Expectations were lower. But - we also didn't have health insurance, because many (if not most) small businesses did not provide it. It's still that way in my home town. I guess that's where I draw the line. I don't necessarily think that anyone is more deserving of health insurance.
People with high paying jobs get insurance. People who don't work get Medi-Cal (or whatever your state's version is). But the people in the middle? Why do they get screwed?
Anyway, now I'm just going off on a tangent. Need more coffee.