"Amex cards account for approximately 24% of the total dollar volume of credit card transactions in the US"
Personally I use amex for all large transactions because they give me a cut (I think around 0.5% cash equivalent?) in air miles, but don't usually bother with it for small transactions because I don't want to risk it being turned down, or take the piss with small merchants who might suffer from the processing fees.
Perhaps this kind of behaviour explains their bigger cash volume, rather than their customers necessarily being bigger spenders in total across all the cards available to them.
I always lead with my Amex, even if I know the place doesn't take it. Merchants need that kind of feedback from their customers. If they won't take Amex, I've got other cards, but I always prefer to use either my Amex or my Discover (another card with spotty acceptance).
Personally I use amex for all large transactions because they give me a cut (I think around 0.5% cash equivalent?) in air miles, but don't usually bother with it for small transactions because I don't want to risk it being turned down, or take the piss with small merchants who might suffer from the processing fees.
Perhaps this kind of behaviour explains their bigger cash volume, rather than their customers necessarily being bigger spenders in total across all the cards available to them.