: It's simply due to brand recognition. Honda has very carefully crafted an image over the years that they're reliable and that quality is paramount. Mazda still has the perception that overall performance is their mantra.
: Look at the demographics again. The US is one of the most valuable automobile markets outside of China right now. And the US mostly shuns manuals. It's a matter of market taste and Americans just can't seem to be bothered about shifting themselves. I'd be interested to see the ratio of cars installed with paddle shifters vs. drivers that actually USE them. I bet that's somewhere in the 6% range as well.
Funny story, and true. When Porsche was asked back in the late 1980s if they would install cupholders in their cars, the engineers threw a fit. "Why would you want cupholders in a car? You're supposed to be driving it, not having a picnic in it!" The rest of the world use their cars for driving. The US seems to be one of the only countries where our automobiles seem to double as mobile offices or homes away from home. I'm guilty of it at times. If I'm running behind on field calls, I'll grab a sub and a tea and lunch while I drive. But back on track.
How engaging can a car be to drive if you limit your interaction with it? A majority of auto enthusiasts will side that the more interaction with the car, the more engaging the drive. For me, nothing makes a road more fun then being able to shift the car and have it stay where I want it rev-wise. Using a little paddle on the wheel isn't engaging. It's just a per-programmed computer algorithm. Using your left foot to engage the clutch and your right arm to select the gear is far more engaging.
Then again, maybe I'm just a 40yr old dinosaur that doesn't get it. One thing is clear. You will only get me to drive an automatic when I can no longer use a clutch.
I don't wish to draw out a debate or argue over the mater, so I'll leave this angle tabled.