Sure, but the barrier for the ISP to allowing the same thing for a proprietary music streaming service has been lowered.
This is, apart from the utility that it brings, advertisement for the operator:
> Wikimedia recognizes the user is on that operator's network and serves a banner on the top of the page indicating free data courtesy of their mobile operator, which reinforces a positive brand experience for the operator. [0]
It's not inconceivable that the ISP would do similar deals with $music_streaming_service. Maybe for some payment.
This is, apart from the utility that it brings, advertisement for the operator:
> Wikimedia recognizes the user is on that operator's network and serves a banner on the top of the page indicating free data courtesy of their mobile operator, which reinforces a positive brand experience for the operator. [0]
It's not inconceivable that the ISP would do similar deals with $music_streaming_service. Maybe for some payment.
[0] https://wikimediafoundation.org/wiki/Wikipedia_Zero