I think the main thing is that we expect the action of the power booster and when it isn't there it takes a while for us to get used to it.
The hydraulic action from earliest thirties on have similar braking action to those today with a similar non-boosted system.
The weight of the old Chevrolet

is much more than the weight of a car nowadays

The new plastic ones now have much more braking action over weight ratio than those old ones (read shorter stopping distance).
Although we could (and can) lock up all four wheels it takes a little more pressure on the pedal for our non-boosted systems. Thus, it seems that our old systems are not as reliable and take more distance to stop than a more modern and lighter car. And, they do.
I think Chipper may tell us that it is simply a mater of physics, i.e., master cylinder bore, wheel cylinder bore, brake shoe/pad surface to drum, and weight of the mass being stopped and foot-print of the tires. Sounds reasonable to me.

Involves some of Newton's laws.
I do try to stay farther back from the car ahead when I'm driving around. Besides, I have to face the fact that my reaction time is not as good as it once was.
Charlie
