The Buffett-Gates Giving Pledge was met with glowing press coverage in the U.S. But in the U.K. and on the Continent, it was largely met with jeers.

Writing in the Guardian, columnist Peter Wilbywrote that letting rich people decide how to solve the worlds social problems is dangerous for democracy.

Yet some of the toughest criticism has come in Germany. In an interview with Spiegel, Peter Krämer, a Hamburg shipping magnate and multimillionaire who has donated millions of dollars to schools in Africa, criticized the tax-breaks given to American philanthropists.

"The rich make a choice: Would I rather donate or pay taxes? The donors are taking the place of the state. That's unacceptable."

He added that given America's "desolate" social system, "it would have been a greater deed on the part of Mr. Gates or Mr. Buffet if they had given the money to small communities in the US so that they can fulfill public duties."