Brake lights with 5 bars

I've been stuck in traffic while driving a lot lately.  Why don't car brake lights show how hard someone is braking?  It seems to me if we standardized on a size of brake light that could go on the back of every vehicle, that we could have 5 bars on it.  When the driver is braking hard, all 5 bars would be lit, when breaking moderately, only 3 bars would be lit, and when just tapping the brakes, only one bar would be lit. Maybe I'm just a sucker for standards like this.... but this idea would save everyone from having to evaluate the distance and speed of multiple cars while in stop and go traffic and would probably prevent a lot of minor accidents.  Somebody should start working on this.