Re: I'm with Ms. Swift
Odd, I don't recall Spotify and their ilk being particularly generous with the ol' moolah either, and their free ('ad-supported') offer was no three-month lure either. They're also famous for not paying much, (if anything), to the artists; it's the publishers who get the dosh.
Apple still offers their conventional iTunes music "buy to own" music download service. Apple Music merely offers an additional method of getting access to music. And – oh, look! – Ms. Swift's oeuvre is still available in the iTunes Store! Including "1989 (Deluxe)" at a mere €11.99! So, she seems quite happy to take the Apple shilling when it suits her.
As others have pointed out, Apple aren't forcing artists or publishers to take part in the free three-month opening. Ms. Swift's complaint would be more valid if Apple were going to offer her catalogue of music for free *without* her permission.