A controversial bill that would require all new cars to be fitted with AM radios looks set to become a law in the near future. Yesterday, Senator Edward Markey (D-Mass) revealed that the “AM Radio for Every Vehicle Act” now has the support of 60 US Senators, as well as 246 co-sponsors in the House of Representatives, making its passage an almost sure thing. Should that happen, the National Highway Traffic Safety Administration would be required to ensure that all new cars sold in the US had AM radios at no extra cost.
My understanding is that the EU – higher density, more languages (so more radio stations that nearby people can’t use), more-congested radio spectrum – has done this, forced a switch to digital car radios, and has generally placed more weight on ways to acquire more usable bandwidth.
The US, without the same level of pressure for the frequency spectrum, has placed a higher priority on not breaking compatibility, keeping existing devices continuing to function.
https://en.wikipedia.org/wiki/Digital_Audio_Broadcasting