Potentially, but the point is that signallers should physically be unable to allow trains to proceed, and drivers should physically not be able to override them. British signalling from the 1800s has physical interlocks; this isn't a matter of manual versus automatic train operation. It is clearly systemic.
Drivers are absolutely still needed for other parts of the operation though, like working stations, shunting, and perhaps most importantly handling irregularities. Faults can happen and you don't want the train to be stuck out on the track for hours. Instead, it makes so much more sense to either fall back to lineside signals (often accompanied with a point-based train protection system) or driving within line of sight.
If signaling worked properly then it wouldn't matter whether the train was driven autonomously or not, the "problem" becomes trivial. Establishing and continuously verifying that signaling is working properly is the hard part.
Without signaling you're limited to crawling speed just like humans are when they don't have any signalling .
The reason vehicles are still driven manually is because humans rely on transportation every day, all of the time.
The current system is basically that the train is driven both automatically and by a professional attentive driver at the same time. Changing it to just the automatic system is going to reduce safety. Also the real world is way to messy to reach acceptable availability rates with only automatic systems.
[1] https://www.itf-oecd.org/sites/default/files/spain-road-safe...
In this case the “object” was another train. That’s not the “hard” part of the problem. This sounds like an apologist comment.