To me the biggest issue isn't so much the fact that it was horse meat. Either you eat meat or you don't, and whether it's beef or horse doesn't make it rationally any different. The problem is what it implies, which is that the operation is so vast and enforcement of regulations so inconsistent that the seller doesn't really have any idea what is on their shelves, nor can they trace it back to solve a problem when one arises. This is a problem even with non meat products.