Jesus there's a lot of ****e on this thread.

1/ imagine a motorcycle front wheel and brake, it makes things easier.

2/ in the old days iy would be cable and shoes, now it's hydraulic and
pads

3/ hydraulics give a mechanical advantage, the smaller "operating"
cylinder vs the larger "operated" cylinder, but the flipside is you get
less travel on the larger diameter cylinder

4/ if the "operating" cylinder displaces 1 cc of fluid, this doesn't
necessarily mean there is any pressure of note in the system

5/ After you take up the slack on "off" or "released" brakes, then,
apart from compressibility of the pad and friction material, generally
speaking each extra amount of fluid displaced by the "operating"
cylinder will inclrease pressure (yes, fluids are supposed to be
incompressible, but brake lines expand etc etc

REALLY IMPORTANT from some of the **** mentioned above.

psi or any other pressure measurement is NOT a force measurement and is
nothing like a force measure ment

single piston hydraulic press type system versus opposing (identical)
pistin brake caliber type system, with the same pistons, piston area
and pressures YOU DO NOT get double the force, you do not even get the
force evenly applied to both sides cos it already is, what you do get,
and all that you get is a floating caliper. this means you get a disk
that is being gripped instead of deflected, this means a hard cast disk
can be MUCH thinner = much lower unsprung weight

to the OP, the television person was talking complete ********