I have, from my experience as a teacher of hand-tool woodworking, a
somewhat different spin on this.

Question, how many of us in the preservation trades are ever approached for
instruction by applicants who are not the products of educated, upper
middle class households?

There are trades and trades. There remain trades like automobile repair,
electrical installation, roofing, etc., etc. that are attractive to folk of
a blue-collar background, where the level of skill and discipline and
acquired knowledge can be very high, but is fostered by  cultural
familiarity and class association; where the grammar necessary for
participation isn't a reach.

Then there are trades that exist to support a world-view that is alien to
the working class ethos. These can be close cousins of the traditional
blue-collar trades, but the grammar of participation can be very foreign to
someone brought up without exposure to upper middle class values. For 28
years I have been often approached by products of the latter, who, having
rejected much of their own class' intentions for them, see what I do as a
more ethical and romantic alternative. Only twice, sadly, have I been asked
for instruction by someone who's family might have association with trade
skills.

For the sake of the continuum of tradecraft I am glad that anyone
approaches me, but my experience has taught me that very few of my students
and apprentices have the wherewithal to overcome the impulse to instant
gratification that is common to their class in this place and time. Mostly
they run off, half-taught, with very little patience, especially, to
explore the historical background or aesthetics of their craft and set
themselves up as bespoke providers to the less discerning members of their
own class. The best of them, all too few, have stayed with me for years,
because they understood that there was just so much to learn.

My ideal, which I have tried in vain to get the State of Maine to see as a
valid component of its vocational system, is to support the kind of
education I give my students as an alternative to the current voc-tech
offerings and then to give me, and others like me,  a chance to win some
working class kids over to our side at school job and education fairs.
Still trying after all these years.
Bruce