@annaaurora I know that NS did this in an experimental pilot for a bit; using a platform-wide lightbar that showed color indicators for how busy each carriage on the impending train would be, so that you could station yourself in the right place ahead of time.

More interestingly, it didn't use any sort of invasive tracking; apparently the system that counted each carriage's busy-ness was entirely based on IR sensors at the doors counting passages, and it worked fine!

Unfortunately the pilot was not expanded; the lightbar was removed (for power cost reasons, I suspect), and the busy-ness indicator on the website and in the app is train-wide now :(