Sticking to HTTP enables transparent caching. So it's not that MacOS/iOS try to connect to anything on the local network, they just connect directly to Apple vi

Sticking to HTTP enables transparent caching. So it's not that MacOS/iOS try to connect to anything on the local network, they just connect directly to Apple via HTTP which allows the local network to hijack the connection and serve a locally cached copy instead. This kind of thing is more common than you might think on corporate and institutional networks because it can produce appreciable savings in bandwidth to the internet. Squid is a very common open-source solution for transparent forward proxy, but there are commercial products that are more common. This kind of "friendly MITM" is sort of the baby that goes out with the bathwater on mandatory HTTPS, although I am personally of the opinion that it's not a big enough deal to block mandatory HTTPS---but there is debate there.