Originally Posted by
AllieKat
It's not. It's the same standard, just a lot of banks implement only a minimal feature set (and Visa encourages this, Mastercard discourages it, and American Express REQUIRES the full feature set is supported). It's the exact same in Canada... so it isn't just the US. I disagree with it, but it is what it is. One more reason Amex is best for travel.
Now, Japan, they use a different contactless standard. That's irritating.
Mastercard is the best, IMO. AmEx has extremely limited acceptance abroad depending on where you're going, uses forex rates that are likely in between MC (best) and Visa's (worst) and also apparently mandates MSD-only contactless for US cards on mobile wallets. The one upside of AmEx is DCC protection but DCC itself is avoidable most places if you know what to look for/do.