American Express Membership Rewards - Amex vs. Diners abroad

I just got back from the Czech republic and I couldn't believe how few places took Amex. Hardly and cashpoints took the card either. However Diners was taken everywhere. The symbol was on the window of every single shop along with MC and Visa.

Why is Amex accepted in so few places and Diners accepted everywhere?

How come Diners doesn't have this ammount of acceptance everywhere else?

I agree that Amex is not that great in CZ but a lot of cash points do take it even though they do not have the sign on them. I have no probelm with the card in most hotels and resteraunts in CZ when I visit.
On the flip side I have just spent a couple of days in the west of DK and AMEX is accepted all over the place even in tiny B&B style places and the Dinners club symbol is not so common.

Also in Italy, Diners is accepted almost everywhere. In the US Diners is almost worthless.

It varies greatly in the chocolate producing countries. In Sweden Amex has almost universal acceptance (in my experience) and acceptance is better than Diners when in Germany, Spain (as far as I can tell) and the UK.

as its cards will soon be processed as MasterCards, if an establishment doesn't directly accept the Diners Club card. For Canadian and U.S. customers, they will soon receive new Diners cards with the MC logo on them.

For Diners Club customers in other countries, it works differently and a little more confusingly. I think their cards will have the MC logo on the back of their cards, and they can use them at U.S. and Canadian establishments that accept MC.

The big criticism of Diners has been its low acceptance by merchants. Because of this, it's been a niche card for many years, even though it basically invented the credit/charge industry back in 1950.

This alliance with MC dramatically changes that. It may now become the most widely accepted card in the world, at least for North American cardholders.