Besides laying bricks, brick layers who really understand their craft can supervise and train others on proper technique. Here's an excellent article lamenting the lack of "master masons":
A master architect and a master mason
Back in 1891, when the Citizens Bank building was under
construction, there were two essential people on the job
site. One was the architect. I imagine that the architect —
someone who clearly cared about water management details —
visited the job site regularly. The project was also
blessed with the presence of a master mason — perhaps a
recent immigrant from Italy — who knew how to sift sand and
wield a trowel. Both of these people oversaw the work of
others, and both insisted that every worker on the job site
needed to adhere to high standards of quality.
The results of their work included the impeccable mortar
joints at the Citizens Bank building.
That sounds great, but, we don't have a huge exponential growth rate or short lifespans.
So, you can easily end up with vastly more people with 25+ years’ experience than <5 years’ experience. That's not a problem for programing or electricians, but for highly physical skills your body breaks down and you don't need 3 supervisors for every worker. For some jobs older workers are simply worse.
Now, with a solid general education these people can move on to less physically demanding work, but trying to plan out the economy 40 years into the future is a bad idea.
Depends on the field. This does happen in fields with low turnover and high longevity. The point is if you want to railroad people into apprenticeship programs you need to limit it to fields that people can do for 30+ years.
Otherwise as I said in a different post you end up handing out medical disability early retirements to lots of people which is extremely expensive.
