I've worked on competitors to the mb system from legacy auto; generally the way we work is make the best possible system for the long term, then limit the odd to meet safety, regulatory, and brand risk requirements.

So there will be a system happily running producing target driving paths, but some monitoring system disables in the case with no car in front.

I would guess that the mb system is in fact ok without a car in front, but didn't hit their appetite for risk yet.