Once you hit a certain scale different dynamics may kick in but even then, outsourcing is an option.
As a freelancer these days, I bring my own laptop and am granted access to stuff for the duration of the project. It's understood and expected of me that I do such things as encrypt disks, use 2FA, and don't use "secret" as the password. Most stuff I access for these projects is SAAS based. I'd probably walk away from projects where that wasn't the case.
Let me guess: most of your recent experience is with relatively new and/or small companies, probably in the tech industry.
No.
> I would expect people knowing how to use a computer and what they need to do their job.
Yes, but their job generally isn't maintaining the computer or it's supporting infrastructure (networks, shared servers, etc.) or, outside of dedicated programmers, programming the computer even as an incidental task. IT exists to do (or coordinate contracting out for) those things, and the last point—restricting programming to dedicated programmers, has pretty much monotonically increased since the 1980s, when incidental programming was both more common than now and frequently projected to become increasingly common (lots of people said all good jobs would require some.)