We are not all like that mate and people still shouldn’t mess with gas unless trained.
I know we aren't all like that, but you can well understand why the industry has such an awful reputation. I note that my thread in the Gas Installer required forum has received zero interest, so I can only assume all the good ones did the sensible thing and ran as far from Colchester as they could.
One guy I used to use and who had seemed quite good got struck off the register. I did know another guy who also seemed quite good, not that I actually met him myself (though he was at least reassuringly expensive), but he did make me wait a month for a repeat annual boiler service before finally telling me he simply wouldn't have the time (as he no longer does domestic).
Another guy I've heard of installed a boiler but hadn't had it it setting mode when he set it up, so it wasn't correctly commissioned. Luckily the manufacturer sorted this out and commented 'it happens often'.
So, just personally, I've been through 5 gas installers and found, perhaps, only one good one. Let's hope I'm just unlucky because, so far, 80% of the local ones are not very good. If I based solely on my own experience, I'd have to draw the conclusion that whatever training people do for their membership of Corgi and now Gas Safe does not give (or is not enough to give) a competent person.
You will well understand that, in my own home, with my relatively simple Potterton Profile, I would be more inclined to trust myself than a random technician/installer from the Yellow Pages when it came to the fan, pressure sensors (they only register a pressure or lack of: no proportionality involved), theromocouples, thermostats, solonoids, and the pcb, though I wouldn't be happy setting up a gas valve.
Quite honestly, I do know someone I would trust with it, but he hasn't been Gas Safe or Corgi since the 80s, so he wouldn't be allowed to touch it either! Obviously one of you horrible lot would be welcome.
In the meantime, I just don't have it serviced and keep it under observation. If I suddenly disappear, you'll know why.