Despite what the law states, these lights have bad usability. A coundown means that is the amount of time you have left, meaning you can carry on your task up to the length of the countdown. Even a 12 yo kid knows this. Take a microwave oven. As it counts down it continues to do its work.

Cars are inadvertently using these countdowns to gauge whether they can make it through the intersection. This glancing at the countdown takes away precious attention that should be, going through one of the most dangerous areas for driving, concentrating on hazard detection and safe driving.

You can design any type of human system, but if it contrasts with standard behaviours, you will have non-compliance. There are unintended consequences for drivers not taken into account by designers. The design needs to be tweaked, overhauled or trashed.