I would say that DCC in the US is more common than we think. Just because we don't see it doesn't mean it isn't there. Far more likely is that there is a critical mass of USD cards, so DCC rarely comes up.

I've asked those with non-USD cards about DCC in the US, and many have said certain chain restaurants have DCC with various levels of hassle to disable. (Oftentimes the waitstaff doesn't know what's happening.) I've witnessed it firsthand with my sister-in-law's AUD card at a number of big box retailers. Not too long ago, someone with a Turkish Lira denominated card encountered DCC at Best Buy, which I would guess is standardized across every US location.