Well, the difference is obvious, if they’ve ever tasted both. If they’ve never tasted horse meat, I suppose they could be fooled into accepting it as beef.
Nut is horse meat actually cheaper than beef over there?
Here n America, edible horse meat is quite a bit more expensive than beef.
If you never have been told that this is horse, not beef, you couldn’t know and if restaurants that want to cut the costs use horse or donkey instead of beef I assume it’s cheaper.
I do remember a scandal back in the mid 70s about ground horse being served in american schools, no idea if it were true or not, but it was common for us to call anything made with ground beef other than hamburgers ‘monkey meat’ or ‘horse meat’
That being said, I have deliberately eaten horse and found it quite nice, more than comparable to bison/buffalo. Very lean, very sweet and mild meat. I would love to be able to walk into a grocery or butchers shop and buy it. sigh I miss germany. I do hope that someone will start selling it locally. We have actually discussed getting a horse at a local stock auction and knacking it ourselves but that would be a hell of a lot more work than one of our sheep.
It’s a specialty meat, so you just have to pony up.
Why drawings and not photographs? 
Photos would be hard to standardise, and while white markings would show up well, whorls wouldn’t. The drawings look like this. White markings are outlined and hatched in red ink, whorls are marked with an x, and scars, brands etc are also marked. There is also a written description of the markings, which has to correspond with the drawing.
These drawings had already been standard for horse vaccination cards for ages. The main advantage of the id drawings over microchipping is that anyone can identify a horse from a drawing, whereas you need a scanner to read a microchip.