At the same time, they face higher barriers to enter their rivals' home markets than foreign firms face entering US markets.

FORBES: United States

Creating further barriers to enter teaching might make sense in order to make teaching a more desirable career in the long-term, but it could easily create even more artificial scarcity in the near term, risking an even wider teacher shortage.

FORBES: Reforming Teacher Pay to Attract New Teachers

The barriers for companies to enter the rare-disease drug market are already high, he says, and families don't want to make it even more difficult by arguing over natural-history studies.

WSJ: Families Push for New Ways to Research Rare Diseases

Perhaps because, despite the crumbling barriers that have allowed women to enter the halls of once all-male enclaves such as Princeton, so much remains unchanged.

CNN: Women, don't marry young