Signalling systems are never simple.
The LZB system, which broke down, had the data you describe. It knows when trains pass over fixed sensors so it computes where they are, and sends data packets to specific trains informing them their current speed limit, and the next, and how far away that is. If the driver won't slow down, the train will.
When LZB broke down, they had to switch to their other system, BSL (fixed block signalling: https://en.wikipedia.org/wiki/Automatic_block_signaling). You can then know the distance to the next block, and if it's occupied or not, but not where the train is inside the block. You can only guess.
In the next few days we'll likely find out if the control centre also fucked up the block signals...
I'm wondering why don't they use GPS as a redundant data source too.
There is a system that does exactly that, its called ETCS Level 2: https://en.wikipedia.org/wiki/European_Train_Control_System
But its not so wide spread unfortunately.
Also if it fails then you are back to operators taking decisions
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