Apple Music's big problem is that the service itself offers nothing new - most of the people that are going to paid for paid music will use Spotify already, and getting them to switch will be hard.

I suspect that Apple knows that the take up for the three month free trial will be huge, but that conversion to paid will be a much harder row to hoe.

This is all about Apple not wanting to foot the bill if and when people switch back to what they were doing already (Spotify, YouTube) without paying Apple a dime.