It's really not about privacy though, the insight needed (not that I'm saying it was easy to make this particular prediction) is that Apple is all about the Walled Garden. It can't be Tor because Apple doesn't own Tor, and so that's not inside the Walled Garden, whereas "Apple Undercover" even if it were functionally no better or worse than Tor, is magically blessed by the Apple branding. And Apple have been all about Walled Gardens for decades.
Tor has reputation problems. Lots of services block tor exit nodes because of all the abuse that comes from them.
By making it a feature for paying subscribers only, Apple probably hopes that their solution won't be interesting for criminals. (Apple will likely cooperate with law enforcement)
