How do you explain the popularity of work teams in the us when its culture places such high value on individualism and individual effort?

Answer 1

It's nothing more than a false ego. People have to work in teams to get any major project done. Bill Gates for example is likely the first name when mentioning Microsoft, but there have been and still are many hands involved many of them so

involved that Microsoft would have never made it if they were removed from it.

This is what capitalism brings, wealth and acknowledgement for the few when there are many hands involved.