“An analog radio could be tuned offset a bit to pick up higher frequencies.”
The trade off being an increase in distortion and low end loss.
AM tuners (most of them) just don’t pass “high fidelity” aural bandwidth. If you stop and think about it, what would be the result of a tuner allowing extra bandwidth for AM detection? It’s called adjacent channel interference. Just because the next slot up the dial is hundreds of miles away does not make the tuner immune from such interference, especially if the sensitivity of the radio front end is decent. Loosen up the selectivity (ability to reject off frequency signals) and you will be bombarded with ACI. All the marketing hype, good intentions, and possible increases in the transmitted signal just don’t mean squat. Any modification to a transmitting device requires type acceptance and type approval. Pre-solid state exciters and transmitters were built knowing the limits of the typical receiver.