Right, but what's different about the way FlightRadar tracks planes? The planes themselves know where they are and can't that be communicated?
FR24 is a combination of ground-based radar (both primary and secondary surveillance) and ADS-B data.
TCAS (as I understand it) uses the transponder part of secondary surveillance radar, but with out the bearing/ranging info, as well as ADS-B (if equipped).
TCAS is useless in the terminal environment, like while landing or taking off. If it wasn’t inhibited (which it is) it would be correctly screaming that there are about to be a dozen airplanes too close for comfort every single time it got near an airport.
It’s a system for avoiding mid-air collisions not stuff like this.