Personally, I think if you are eating beef then horsemeat isn't too far of a stretch, as long as the same humane slaughtering practices apply to both species. Many horses live horrible lives outside of factory farming zones and feedlots. They are abused, overworked, and used for entertainment. So steer may in fact live better lives than horses before ending up as beef. If horses don't end up on the dinner table, they are rendered into products that we ALL use on a daily basis. They are not buried in plots. Can you imagine that???
However, I do take issue with processing companies misleading fast food manufacturers and the public at large. Then again, I also kind of adhere to the mantra, what you don't know (oftentimes) won't hurt you.