You've said that few times Jug but the info you have given in the past is good to repair a type 1 red key (you say press a soldering iron against four lugs where the red 156 key has only 2). I'm pleased that this worked for you and solved your relatively simple problem, but I wouldn't encourage everybody to have a go at it.
Black keys are even more difficult (often opening them for a start) and if it was a case of just a few dabs with a soldering iron then you are right, everyone could do it.
The reason they don't is the same reason that people take cars to garages to do jobs which I am sure you personally are quite capable of doing yourself - not everyone is technically minded and good at that sort of thing and not everyone has the time/tools/inclination.
Having personally fixed many keys with rotted circuit boards, dry solder joints, loose IC legs and missing sub-miniature components you can be sure that what seems to be a simple job of a loose switch very often isn't, and this is where good tools and professional experience come into play.
Without a doubt, the worst keys I see are the ones where someone has tried to fix it already and made a terrible job of it. I reckon I fix 99% of the keys I see, and about half of them have serious faults. By fixing the key and saving having to buy a new one and recode the car it saves people a lot of money which (honestly) as an Alfa lover gives me a lot of pleasure. In nearly all cases the ones I can't fix are too far gone because someone has taken a standard soldering iron to it and melted off half of the delicate components around the switches.
Clearly it is a free choice and clearly people should be empowered by information on sites such as AO, but be careful in giving blanket advice to help people do repairs when that advice does not apply to all situations