Is the radio handover not already happening in the US? It is on FM in Europe. To quote the venerable BBC, “If you listen to FM radio while travelling around the country, you may often need to retune your radio to another frequency for the same station. Many car radios have RDS (Radio Data System), which automatically tunes to the strongest FM signal, so you don’t need to retune the radio manually.” The same thing happens across other European countries.