What car do you have without power steering? Or, are you referring to electric as opposed to hydraulic power steering? I haven't seen a car without power steering since the early 00s (which was a 90s car).

The steering deadzone is not purely a function of power steering. Some of it is design or could be attributed to that, but a bunch of it also comes from slop in the physical connections in the steering column, as well as the suspension bushings, your tyre profile, etc.

I once drove an early car with an electric steering assist system. (It was either a renta or a test drive, I think it was an American car, and I don’t remember what brand or model.). It was terrible. There was essentially no feedback from the road to the wheel.

These systems have improved.

It turns out I was mistaken! I haven’t done enough research to determine the actual cause of the effect I have noticed. It might be hydraulic vs electric but I don’t want to make that assumption and be wrong again - I’m going to have to research the steering in other cars I’ve noticed that issue in.

There’s definitely a different feel to the electric motor driven assist. Though there are just many different implementations probably the specific one you had was particularly quirky.

Relatedly I had a Hyundai i30 for a while which has a well known fault where the plastic gear connection (called a Spyder Bush) from the electric motor to the steering column would break. Resulting in slop and a clunk. Not hard to imagine similar failures or bad design.