This year, a new Oxfam report entitled "Working for the Few" underlines the fact that the world's 85 wealthiest have as much as the 3.5 billion poorest. Oxfam chief executive Winnie Byanyima summarized the point well:
It is staggering that, in the 21st century, half of the world’s population - that’s three and a half billion people - own no more than a tiny elite whose numbers could all fit comfortably on a double-decker bus.
The report encourages increased taxes on the rich and better use of that revenue for universal healthcare and other programs. Unsurprisingly, the United States is mentioned in the context of laws and tax policy favoring the wealthy.
The point, of course, isn't animosity toward those who have more. The point is the imbalance, which is artificially maintained by governments tending toward policies that favor the top income earners. More equitable tax policy, for example, would simply ensure that the wealthiest in a given society pay what they owe. This is not a case where the rich need to charitably "give back," but to make obligated payment to the country from which they have benefitted.