Being a pilot/flight instructor isn't really like a blue collar job in the true sense of the word. I don't know any other trade professions that come anywhere close to the levels of studying, discipline, cost, and the amount training and certification that's required to become a professional pilot. Not to mention the numerous financial and other obstacles aspiring pilots face trying to get into this industry.
Being a professional pilot I guess technically is a trade job, but it doesn't really have the appearance of a trade. It appears more like white collar. Blue collar workers generally tend to avoid reading books and developing their cognitive abilities. White collar workers on the other hand, generally do like reading books and studying. Pilots fall into this category. Blue collar workers never need to know about the fundamentals of instructing and how people learn. It's as if professional pilot is a mixture or a blend between white collar and blue collar. Some professional pilots have deskjob duties/administrative jobs and management roles within an airline/corporate department, etc.
Flight instructors are teachers, not plumbers or carpenters. Quit making it seem as if CFI's don't matter and that the services they offer aren't worthy of compensation. This will just take us back to the 90's.
On the subject of true 'blue collar' jobs, I used to do blue collar jobs. The type of work you do as a blue collar worker is unforgiving on your body. It's hard work physically speaking, and lots of blue collar jobs suck. Many of those types of jobs are dangerous, and safety is not on the minds of a lot of blue collar people. I have seen it first hand many many times. Many have a total disdain and disregard for OSHA regulations. Also, there is little to no cost to get into most trade professions unlike going to college and getting a degree. I don't know ANY blue collar guys offering FREE services to anybody they work for. If anything, many of the more skilled workers are making close to 6 figures or more.
The average blue collar person is making more than your average CFI in this country because people like you choose to lower the bar for everybody. Nicely done man. Tradesmen don't have an incentive to lower the bar and offer services/skill sets for free or at a super low cost. They're not 'building time' the way pilots 'build time.' They're building a bank account and just need to make a living and pay those bills and have some extra money in their pocket for their days off, saving for retirement, vacations, etc. Maybe your not doing what the OP is wanting to do but your obviously encouraging it. Plumbers, electricians, roofers, landscapers, repairmen, etc., don't sell themselves short the way pilots have been doing for so long. And if they do choose to lower the bar and offer cheaper rates, they don't do it as cheap as some pilots would do things for.
Anything outside of aviation typically pays people what they're truly worth, with some exceptions. However, in aviation, you throw an airplane into the picture, and people start cutting eachother's throats to do the job for free or nearly free. All because they want to fill in those columns in the logbook and 'build time.' If we would just STOP encouraging this practice, things would improve. But when we encourage it, people will always be scratching their heads wondering why CFI's don't make anything.