The best way to realize that is to go to a one or two day course in which numerous people--women, big men, smaller men, police officers, ranked competitors, and new students--shoot at steel plates.
I have, of course, observed a lot of the same things. As a general proposition, if you hold all else equal, someone shooting a less powerful round will be able to shoot subsequent shots sooner, and will have to devote less effort to avoiding marksmanship issues arising from pre-ignition anticipation.
That said, with a suitable gun, excellent technique, and adequate grip strength, it is absolutely possible to shoot the same kind of splits with, say, major power factor .40 as with minor power factor 9mm for targets at close to moderate ranges... because in both cases the gun can be controlled to such an extent that trigger finger speed and visual processing time are the limiting factors. So I would disagree with the claim that "
Every shooter can fire a service-sized 9MM more rapidly than comparable .40 or .45."
To go to a relatively extreme example, let's look at some slow-motion video of Charlie Perez. Charlie is a big guy with exceptional hand strength. He's shooting a big gun. He's shooting major pf .40 cal ammo in this video. With the level of recoil control that
he has, recoil is not the limiting factor in how fast he's able to shoot at moderate distances.
Similarly, I took a Ben Stoeger class a couple of years ago where he ran his Production division gun (with 9mm ammo) one day and his Limited division gun (with 40 ammo) the next day. He didn't shoot worse or slower with the Limited gun, but he did say that he has to pay more attention to grip and recoil control.
I would say that there's the level of recoil that a given shooter can handle fairly well with ease, the level that they can handle fairly well with some effort/attention, and the level that begins to impact performance even when attention is being paid. Those lines fall at different places for different people. There are a non-trivial number of people who can get that second line up above .40, .45, and even 10mm. Where that line is for a given shooter absolutely depends on things like technique and hand strength.