I don't see why this is an issue. If it fails, the train should stop. The train should be designed such that it only continues on its way if a continuous "okay

I don't see why this is an issue. If it fails, the train should stop. The train should be designed such that it only continues on its way if a continuous "okay to proceed" signal is received, gated on automatic safety systems and deliberate human action. Even if you have a driver, the train should still stop if it cannot communicate, because the driver can't determine whether the track ahead is safe.