Amex (and other CCs) walk a fine line. End customers are what makes things tick. To get more of them, they offer to side with them in any disputes.
If they abuse merchants enough, they won't accept CCs. But refusing Visa or Mastercard means turning away a lot of customers. Refusing Amex means turning away some. If merchants start turning away cards, the card is less useful. Amex is not a stand-alone card because it sometimes gets turned away. You need a real CC too. Merchants can average things out over time, so while the 1 in 100 dispute is unfair, stressful, rant-inducing stuff, it ultimately only costs around 1%. I assume this is less then what you lose from turning the card away. Since they are businesses, they are obliged to make more rational decisions. This makes them a better target for abuse.
Our office runs just fine on Amex. You might need a Visa if you're charging coffee in the morning to your business. Otherwise, this doesn't ring true to me.
Note that I get why you'd carry Visa/MC debit in your personal life. I just don't know why you'd work with the banks for your credit card.
How about restaurants, small retailers? I dunno. I guess it depends on where you are. If Amex is a stand alone card for you, pretend it isn't. I was just illustrating a point.
If they abuse merchants enough, they won't accept CCs. But refusing Visa or Mastercard means turning away a lot of customers. Refusing Amex means turning away some. If merchants start turning away cards, the card is less useful. Amex is not a stand-alone card because it sometimes gets turned away. You need a real CC too. Merchants can average things out over time, so while the 1 in 100 dispute is unfair, stressful, rant-inducing stuff, it ultimately only costs around 1%. I assume this is less then what you lose from turning the card away. Since they are businesses, they are obliged to make more rational decisions. This makes them a better target for abuse.