That's exactly right! It makes me wonder if (maybe) they don't want to fix it because they sell more rotors and pads because:

[Bike mechanic]: "Yessir, these pads are contaminated and need to be replaced".
[Customer]: "But they're only a year old and I don't ride much".

In the end I could ride the bike once and spray it with chemicals or ride through a nasty puddle with lots of oil in it and contaminate the pads and rotor. It is not a time thing it is a single incident that can cause an issue. I got some mineral oil on a rotor that had very little time on it and tried to decontaminate and it didn't work so I had to replace it. It was hardly ridden but it got contaminated in one incident.

Sometimes alcohol, flame and sanding will do the trick and sometimes it won't.

Might that be because the rotors are much thicker so less vibration? And the temps are way higher so natural burn off of contaminants?

my bike rotors very rarely squeal.

I suspect there are trade offs that lead to the problem. I notice that people like their disc brakes. I've tested them but haven't had them on a bike of my own yet, and I'm not craving them. Is the tendency to squeal a price worth paying for brakes that work better than rim brakes?

I'm reminded of Click and Clack, the hilarious guys on the car maintenance radio call-in program. They used to say: Thoughts?

Well, I have used my disc brakes to very good effect a number of times - once a horse rider said to her friend “wow, they’ve got good brakes” as we rounded a corner on a descent, at maybe 40kph, spotted them heading our way and slowed to a near stop (sans squealing) inside 10-15 metres. They are just so much better than rim brakes.

I don’t like squealing but as above, rarely get any - maybe a bit when it rains.

I’m European if that helps the stats ;-)