Interesting, in 40 years of driving, I've never had a problem with dirty brakes and have never even heard of someone cleaning their brakes. I've never seen it in a manual as a manufacturer recommend activity.
And in most EVs, the brakes are used so much less than in other vehicles.
That is exactly the point. Because the brakes are used much less, they require even more attention. To be in the best condition, brakes need to be exercised frequently. And the bigger the brake system like the 4-piston Brembos on a Model S/X, the more exercise is needed. This goes for all cars with big brakes.
It's not "dirty brakes" as you call it. It's potential rust and seizing. Cold/snowy climates can be very harsh on brakes due to water, salt, residue and lack of brakes being exercised/heated sufficiently on EVs.
One of the reasons why many people don't hear about brake cleaning/lubing, is because it is often carried out when pads need to be changed. On a Tesla however, they mostly don't need to be changed due to limited use.
Brake cleaning is one of the most basic types of maintenance and has been for decades. That you don't know about it or hasn't been done on your previous cars, doesn't make it wrong. There are many other types of maintenance that people don't know about or don't feel are necessary too. In most cases, those who fall into this category have very limited understanding of how a car works. Which is fine - just don't advise people on the subject matter.
People who fall into this category, often also do not feel when a car does not behave optimally. Partly because of their senses and interest in/knowledge of cars. I have driven many cars having issues with the suspension, brakes, steering or engine response. But the owner was oblivious to it.
The brake mechanics/dynamics (and suspension, etc) are the same on a Tesla as any other car. They should be maintained, especially in cold climates and given how little they are exercised. If not, there's a good chance you will suffer the consequences later on and Tesla will likely not cover this on warranty, even if they can be generous at times. Where I live there are quite a few Model S owners who have paid thousands of dollars for seized calipers/pads because they never/hardly use the brakes and didn't service them.
My advice (especially for those in cold/wet places):
1) service the brakes once a year. I do it myself, but otherwise it'll cost maybe 150-250 bucks if it's not included in other service. Money well spent.
2) Set it to low regen and do some heavy braking (3-4 times) at around 40-50 mph once a week. Just to exercise the brakes and wear off surface rust. Will also eliminate brake squeal.
3) Change brake fluid every 2-4 years depending on condition and brake feel.
