All I'm trying to get at, ultimately, one way or another, you end up using a dedicated isolated power supply that is not common with U.
The old way, (black TMCC modules) just needed an aux AC transformers again completely isolated.
The new way (Modern LCS Layout Control System- AKA blue modules) carefully considered their own power supply system that by default isolates them. This also makes the older black modules compatible when using a SER2.