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.
Not necessarily back then more or less every one also has a home radio which often could be run on battery. But the car provided an independent power source that was removed from the grid. For most of the cold war cars were purely mechanical no micro chips to fry. Also vacuum tubes were a common thing which are much more resistant to EMP.