Well, yes and no.
I would challenge the first bit.
I do not believe that people are born with mechanical aptitude.
The left brain-right brain dominance theory seems to hold up well so it might partially support your theory but I believe it is more to do with early childhood education.
My wife is a beter mechanic that I will ever be, yet she did fine arts and taught painting so well a prestigious private school made a position for her then she taught every child in the juniour section 6years to 10 years.
However what we both had in common was exposure to a Meccano set at a very early age.
Nuts, bolts & bits of metal that go together in no predefined form.
As a social experiment the Humanities students interviewed all 9000 students doing engineering based studies at UNSW and over 90% played with Meccano as young children where as less than 10% played with Leggo
The following year they did the Commerse based courses and the inverse applied.
Next year it was Fine Arts whose results were very similar to Engineering.
The following year Medicine students took the same test and oddly enough, for them Barbie came out tops but only just above 50%.
I graduated the following year so never found out what the Law Students played with as children, something that I have always pondered about.
Now as to the situation currently here, small engine mechanics are also in short supply as are auto mechanics for that matter.
To work for a shop you need a trade certificate which is a 4 year apprenticeship with 1 day college each week.
To work independently you need nothing more than an insurance certificate.
An idiot government decided apprentices were doing it tough & mandated they get paid full adult rates while training so none got trained.
Both our major political parties took a big step to the right and sold off all government enterprises to private industry and naturally the maximum profit driven private companies stopped training tradespeople which is not cost effective.
This was made worse by right wing government incentives to castrate organised unions by subsidising importing "qualified" tradespeople from overseas.
As such numbers attending trade colleges dropped so they got closed down and we set of on a self feeding closed loop which gets worse & worse every year.
To make matters worse still, it costs about 1/2 of what you pay a tradesperson in wages to insure them so hourly cost out rates are over $ 100 / hr which makes it uneconomic to repair most small engines when comparred to imported temporary deverted landfill, so the buying public do not get things repaired. Mechanics see their $ 25/hr wages and compare it with the $ 100+ charge out rate and feel exploited so they leave.
Glass fronted showrooms use the workshop as a marketing tool for the sales department by giving outrageous quotes for repair, thus most of what the mechanics do is preassembly which is boring so again they leave .
The only mower shop in my territory takes on 1 apprentice every 4 years. He gets over the seasonal problem by storing all the trade ins taken during the peak selling season and gets the apprntice to do full rebuilds on them over the off season to prepare them for sale during the on season. He looses money doing this as the mark up on new equipment down here is 100% so selling rebuilt trade-ins drops his retail margins but he needs the extra hands during peak season for repairs.
Long term it is a dying industry and most in the industry can see this.
Ultimately pollution regulations will mean all domestic equipment will be electric and like hot metal type setters, bookbinders, blacksmiths, metalspinners & steam engineers we will vanish down to the ranks of craftsman hobbyists,