WASHINGTON (AP) — A massive recall is getting most of the blame for the U.S. baby formula shortage, but experts say the products have long been vulnerable to this type of crisis. They point to decades-old policies that have allowed a handful of companies to corner the market. Safety and manufacturing rules imposed by U.S. regulators make it hard for smaller companies to enter the market. And federal contracting rules also favor the largest manufacturers who can offer the lowest prices on formula. Those government rules are aimed at assuring safe, affordable formula. But they are now getting renewed scrutiny because of the shortage.