In 2015, National decided to end the free XM radio options in most(all) vehicles in favor of a $6/day upcharge.

In my 20+ rentals since October, not once has a desk/gate/booth agent asked me if I wanted to purchase it. I asked an agent about it once and she said "We stopped asking. No one wants to pay for it."

When making a reservation online, XM radio is not listed an add-on option like GPS, etc.

What's the deal?