You don't. In the 00's I was into this tech and largely felt good about the FM implementation, though the initial work did make some very aggressive trade offs

You don't. In the 00's I was into this tech and largely felt good about the FM implementation, though the initial work did make some very aggressive trade offs, some of which may be improved by now. One was receiver side synthesized high frequency sound. Initially, real audio cutoff around 5khz and on a Bangles song, a finger cymbal could not be heard. There were some other issues, and I believe it was bumped up to 8.5 or maybe 10 on higher bitrate streams. Some radios detect the IBOC easily, making seek, scan type functions less useful. My own SONY car radio was impacted. Would tune static, then the station, then static on a scan. On AM the system was not all that robust, but did deliver low noise, but compression artifact laden audio. To be fair satellite radio does too. In order to make it work, AM stations had to use a brick wall 5khz filter. Many stations were running 8khz. Major downgrade on nicer radios. It also required analog AM stereo be removed. Analog stereo worked well and I listened a lot. Fringe areas were good too. Basically the noise floor would come up and eventually the broadcast would go mono, then fade away. Classic AM. IBOC did not work well, and the difference in sound was jarring! Fringe areas were maybe half too, so very limited range. Buildings and other things made a mess of it all. Rural flat terrain AM HD worked! I even liked it. Analog AM Stereo at 8Khz worked better overall everywhere else, but there were not many radios... I could go on, but AM was a mess and few stations are on air today. FM sort of happened. There are plenty of stations and the in car experience has been improved a lot.