They really are there though, even though they might not be immediately obvious!
The thing is, this is a project which essentially ties together two existing regional railway lines through a new underground core. Those two systems have existing rail traffic on them and different signalling systems on each. It's already been a nightmare to implement three signalling systems and transitions between them – a project to provide fully automated operation on two other railways lines in addition to this would ramp up the complexity even further.
Fully automated lines are totally viable – the DLR system in London works in the way you suggest and has for some time. And I'd bet that if the Crossrail project had been a new and isolated line it probably would have been using full automatic train operation throughout. But it's a hybrid between a regional railway and a metro line – ATO is way harder.
At Paddington the driver gets off and the train goes into a siding, then comes back on the East bound platform.
Makes sense, either you have a different driver waiting to board the back of the train, or wait for the driver to walk the 250m of train to get to the other end.
If you haven't seen the technical difficulties that crossrail has run in to then you haven't been paying attention. They've been talking for years about how complex it has been to integrate the 3 signalling systems in use at various points on the line, so I'm not surprised they want a human in the loop in case one of them gets a bit wonky.
It would be good to avoid these snippy comments. Obviously no one can pay attention to everything - we don't have much additional capacity over family and work commitments, so phrasing things as though people are to blame for not knowing enough about a London construction project is worse than unnecessary.
But given that premise, should we not first do away with snippy comments like "why don't they just [..], it's not that difficult"?
https://www.londonreconnections.com/2021/the-political-myth-...
From memory, one of the issues during the last few strikes was that TFL wanted to remove the conductor from some services, only having the driver who would then be responsible for safety. The unions strongly opposed it.
The main point of a train operator is to handle things that automated systems cannot. Things break. Humans need to make decisions fast and be onsite.
When you entire goal is to keep things moving and resolve issues as quickly as possible it rarely makes sense to take the local human out of the loop.