Fly by wire would be a terrible design for a car, I’ve seen people driving on space saver tires or with taped up windows for months. If people already just ignore warning lights until something physically stops them from driving then at least having a physical steering column means there’s still control after the power steering fails so that they don’t go straight on into oncoming traffic.
On your other point about still using the same control systems as a model T, modern cars don’t. Hydraulic steering came around in the 50s and almost all modern cars have electric power steering, the model T had completely unassisted rack and pinion steering. I can’t find any definite answer on what the last car without any hydraulic steering was but I’d definitely like to find out if anyone knows.