>IBM mainframes run the banks.

And the airlines, and the logistics companies

That's a bit unfair to the insurance companies. They have a pretty big say in what happens and also run mainframes.

And mainframes run on concrete floors, maybe construction companies run the world by that logic?

Mainframes aren't a big truck, they're a series of concrete floors.

My usual comparison is with cargo airplanes.

This is becoming less true over time.