When we cross the Cascades or Rockies in our Land Rover Discovery towing an Airstream, we have to shift and engine brake on the downslope for miles (to avoid overheating the breaks) and it's noticeable that the trailer brake lights go red, while the Land Rover doesn't unless I tap the brake pedal.
Indications that the car in front of you is breaking include brake lights, distance between you and them, and weight transfer to the front (nose down, rear up). Only one of those is affected by the thick pedal.
What law says that?
https://oregon.public.law/statutes/ors_811.495
> A person commits the offense of unlawful coasting on a downgrade if the person is the driver of a vehicle on a downgrade and the person coasts with the gears or transmission of the motor vehicle in neutral or with the clutch disengaged.
However, this only refers to going downhill. It says nothing about approaching a red light or any other scenario where you might consider choosing to coast.