It's my view that there's a lot of double-think about this issue.
The fact that horse meat has been found in beefburgers is, I think, absolutely inexcusable, but not for any pseudo animal-loving reason. Why is it OK for cows, sheep, chickens, ducks, pigs, etc., to have miserable existences and then be killed for their meat, whereas people throw up their hands in horror when horses are involved? And let's not kid ourselves that we are more "civilized" because animals are stunned before they are slaughtered - invariably their lives have not been much fun up to that point. And who has bet on the Grand National even though horses are at risk of broken limbs and are then destroyed because they're of no value.
I think that the fact that other animal products, such as horse and pig, have been found in beefburgers is wrong because we should have accurate information about what we are eating - even though people have been assured that the beefburgers are perfectly safe to eat (and can we be sure of that anyway?). No doubt there are lots of ingredients that are considered safe to eat but we may not necessarily want to eat them.
I heard on the news that this coalition government, has hived off the responsibility of monitoring what is contained in a food product to DEFRA, who in turn passed it on to, I believe, local authority food inspectors, who were already hard pushed (due to cuts) to carry out their regular monitoring duties.