Note that OP made a distinction between "need" and "ought to" and I agree. You don't "need" to know any of these, but you "ought to" because knowing them TO SOME DEGREE helps you use the machine more effectively and safely. Networking course is definitely going overboard, but I still think they're important to know. I'm pretty sure doctors already do understand the basics of how MRI machines work.

Learning the basics of how WiFi works avoids people getting confused when WiFi doesn't "just exist" everywhere, or why it drops out suddenly when a lot of people are using it even if you have full bars. Learning about HTTPS and SSL lets you understand what it keeps secure and how that can keep you secure when you're e.g. banking.

That being said computers and software now are specifically designed to hide their inner workings as much as possible to simplify things for their users so it's a bit of a special case.