if people forget to turn off Waze when they get on the train, they are probably going to forget to switch to 'train" mode.
This is the main argument for mapping (but not connecting!) rail lines. Hopefully the client will "snap to" the rail segment and isolate GPS tracks from the adjacent roads.
Yes, some people forget to turn Waze off in train, but this is quickly solved problem with new option "on railway turn Waze to train mode". We will see train on Live map!
In my opinion railway "GPS tracks" are not dangerous, it is easy to ignore them.