On the other hand, on a typical secured WiFi connection over TCP over an Ethernet connection, like 10 times more complicated stuff is going on in protocols and the software stack. It’s not as if we went from bit banging HTTP directly down an Ethernet cable to a hopelessly complex stack of software; we just added another element of complexity at the application layer in exchange for real security and privacy benefits. Example.com doesn’t need it but it has become a best practice for good reason so it is used on most of the net even when not strictly necessary.
Enforcing HTTPS is a best practice because an absurdly overwhelming majority of user agents, like 4 or 5 nines of them, support HTTPS and the redirect ensures they use HTTPS and makes downgrade attacks a little more involved.