The alternative method is just people ad-hoc tracking the aircraft with their own ADS-B receivers. LADD doesnt allow aircraft to stop broadcasting. Only that data vendors like FlightRadar must respect the privacy requests. But antenna owners can choose to share their data with vendors that dont respect the LADD program in which case there is 0 recourse.
You can buy the antennas for like $100 and share the data in real time with whoever you want.