Engine breaking, which any manually car driver uses, does not produce any indication that you're slowing down. Technically, the engine noise is louder, but not enough to notice outside of the car.
You're right of course, but these days engine braking is most commonly used by tow vehicles, whether that's a family car or a big hauler. Either way when towing, these are generally required to have trailer brake controllers that are activated by deceleration so that the trailer brake lights do come on.
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.
You can engine brake in any "manumatic" like Subaru with their flappy paddle CVT. You could drive a manual without engine braking more than a normal automatic; nothing forces you to downshift. You could also only up shift and use neutral when braking with actual brakes, which I think a lot of people do when learning manual.
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.
> 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.
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.