Interesting discussion. Surprised no-one has mentioned the new fangled "Cruise Control", which (on my car at least) will automatically slow the car to match the speed of a slower vehicle in the same lane (once you are within a certain distance of said vehicle), if you move to overtake the slower vehicle, it automatically returns the car to the set cruising speed. No idea if these changes cause the brake lights to be illuminated, but, I assume the initial slowing causes the brake lights to be illuminated.
Maybe it is an age thing, but, in my petrol or diesel cars, I often relieved the tedium of long motorway hauls (particularly in mainland Europe) by maintaining progress without touching the brakes.