I have heard that some restaurant chains divide the ingredients for their secret recipes among several departments in different states. One department would mix part of the seasoning and another would handle the batter.
The companies try so hard to safeguard their secret recipes, so they figure it is best that they dole out information on a need to know basis. The various departments are strictly forbidden to reveal the ingredients to anyone, so even those within the company don't know them all.
Some soft drink companies use this need to know basis, also. The major ones want to keep their formulas secret to deter copycats.