> That is completely false. PTC does that, and we've had it for several decades.

I think you are misunderstanding the sentence you quoted.

It says something about the safety of self-driving cars. That is they don’t meet the standards required for railways. In other words the expected safety for a self-driving CAR is lower than the expected safety of a RAILWAY. (Caps for emphasis, sorry about the shouting.)

Your comment reads as if the quote claims that we cannot make “self-driving trains”. It does not say that.

> You keep pretending that avoiding train collisions is too magical to achieve with current tech

I don’t think that they do that. Definietly not in the comment you responded to.

> That is completely false. PTC does that, and we've had it for several decades.

And they somehow work with radar, lidar and GPS from inside the train? No they work with classical block based systems and on signalboxes. So all the safety systems are outside of a train.

> You keep pretending that avoiding train collisions is too magical to achieve with current tech

Huh?? Railway interlocking exists for more than a century. It's very safe and I didn't wrote anything contradicting that.