I suppose you could discover new bands at home or work on a computer via pandora or last fm or some other streaming music site that does not require a wireless data plan? Maybe you have family or friends who told you about some new band that they saw at the local tavern. Or maybe you go down to the tavern and discover some new band yourself. You could purchase/pirate the bands songs/albums that you dig the most and put them on your iPod, and listen to it in your car. Depending on how much you spend on music a year, and how big your existing music catalog already is, (400+ albums in my collection) the cost in most cases is still significantly less than $700 a year. If everything was pirated, which I don't recommend, the cost is $0.
You could also purchase the hardware and a year of satellite radio for +/- $200. Then it would cost around $120 a year or so depending on the package that you subscribe to.
The internet not only allows you to discover new bands from streaming sites, but you also research your favorite artists to find out who their influences are and then you can check out that music and so on. You can be led down a rabbit hole and come out listening to a genre that you had no idea you liked. In that regard, I certainly agree that to a large extent I've discovered new music via the internet that I may not have known of otherwise. I've had a tough time trying to discover anything new on the OTA radio, what with the same 10 songs by the same 5 artists every hour like clockwork.
The point is that you can discover new bands at a cost much cheaper than streaming music over a smartphone or iPod in the car. Besides, you don't have to have the internet in the car to make 8-10 Clear Channel stations in every city irrelevant. They do a pretty good job of that all on their own.