Ever since Hertz introduced Sirius it has 'monetised' Sirius ; it is something that is offered as an optional extra and never offered as a benefit of status
There are a lot of things it can do, but also no reason not to address where people are aiming to take cars with Sirius but not wanting to pay for it - in OP's case , for example, it isn't just a case of ending up with a car with the facility because the location had no other vehicles, but a deliberate process to choose cars with Sirius whilst not including it in the reservation
Its changing rates for rentals in the US has no bearing on this
Just connect mobile phone via bluetooth and use an internet radio application and issue resolved