Some do, some don't. But most frightening to most investors is the unreliability of the capitalism that does exist. See Kenya, for a recent example. Would you invest in a company in a nation that may, or may not, have a free market to operate in next year? Kenya has, for the past several years, seen tremendous economic growth and development, much of it supported by outside investment...but with the newly elected leadership, genocidal military actions, and a return to the tribalism and cronyism that accounts for the problems in the rest of undeveloped Africa, those businesses are fleeing and the economy is collapsing...with the favorite people of the new president dividing up the corpses of industry amongst themselves.
Russia, while not undeveloped, has seen tremendous investment over the years from outsiders...and a very big amount of that investment has vanished into the void that is a constantly shifting economic picture and the pockets of former KGB leadership who leveraged their power into positions as "captains of industry" as state-run services were privatized into their possession. Same story...if you can't rely on the rule of law to protect your investments, you not only take on the risk of investing in a new idea and unproven people, you're also betting that the government won't rip it all out from under you when it begins to succeed and give it to their favorite crony.
The US isn't unique in offering respect for rule of law (nor is it getting better in this respect), basically free market, and checks and balances to prevent any one person from wielding too much power over businesses, but it has a long and stable history in these areas. Despite SOx, the US is still one of the best places to start and grow a business...and no matter what happens with the leadership of the nation, it probably will remain so for the foreseeable future. This is also why investors like Delaware corporations...well-understood and very slowly evolving corporate law.
So, it's not just capitalism, but consistency: the removal of one variable from the risk side of the equation.