Unfortunately, the vast majority of AM tuners historically have used diode-type envelope detectors, which have inherent distortion, noise, and sensitivity problems. Most roll off the high end at 5 to 10 kHz to reduce adjacent-channel interference.
I don't blame the manufacturers much; there's not been much demand for good AM receivers. Most people think of talk radio, sports, and news when they think of AM. I haven't been following lately who's making what types of AM receivers, but if you can find one with a decent product detector instead of a diode detector, they can sound really nice. Not many people know that despite the 10 kHz spacing on the band, AM stations can actually broadcast up to 15 kHz audio bandwidth. And some do so.
I've been meaning for years to get around to building my own product detector and tap it into the IF stage on one of my receivers. But it slipped behind a lot of other projects, and thanks to this thread, I might get back into it.