Spoke to service adviser at dealer. He said most of the time you get the white message first. But not ALL of the time.

Unit fails before warnings of lower remaining expected life cycles pop up. No indicator other than red light perhaps and no brakes. Sounds like some units do not make the count even till the white light stage.

Here is where it gets really stupid. Unit is still functional but expected life cycles are reached unit gets shut off. Normally I would expect the white warming presented though in that scenario.

You want to play games like this on cars then aircraft redundancy type systems must be employed. Maybe their engineers at that time were doing substance abuse. Or liked Russian roulette.

My guess is either they rethought what they had done. Or more likely some of the units failed very early in service causing accidents. Even electrical faults can probably shut the brakes down. So they just eliminated it from future production.