Could be a bit of a stretch, and this note wouldn't be made public if she didn't sign off on it, but I think this is more measured than an artist just pushing for revenue.
When she previously removed her album from Spotify she implicitly let it be known what her motivations were: maximizing her own revenue, even if it was at the expense of other musicians. End of story. She would rather you give your $12 entirely to her instead of Spotify (or another album), which spreads it around. And I'm totally fine with that decision since she might seriously be the only musician alive with enough juice to get away with it. But the point remains that she's already made her motives perfectly clear, so when she wrote that letter to Apple it was purely about making sure she got paid during that three month trial. Of course, other artists will get to ride her coat-tails some, so she played up that angle and pretended it was a moral crusade. If she tells Apple, "Tell you what, take the money you'd pay me during those three months and distribute it evenly to everyone else." then I'd applaud her. Until then, she's a hypocrite going after more money.