In the Nordic contries it is an ancient tradition to eat horse. The Swedish word for Christmas even komes from the old word for horse and beer, cause at the Midwinter festival you slaughtered horses. This was later banned when Christianity came here cause it was considered barbaric.
Eating horsemeat is still very common here, but it is considered a low budget meat. I have eaten it in the past when I ate meat but I never liked it so I saw no point in eating it. It's sold as some kind of cheap sandwich meat here. Sometimes you can find horse steak, but it's not very popular or common. People just thinks it's a bad, low budget meat.
The attitude here is that when a horse is old it ends up on the sandwich. Most horses are still sent to slaughter at the end of their life, that is the most common way here. Even race horses or army horses that have had a career. I find that a kind of ungreatful.
I don't know how it is nowadays, but you usually had to apply for a special permission to have your horse just put to sleep if you didn't want it slaughtered. Or you could get a hunter to shoot it. Then you still had to ask for permission either to have it cremated or find somewhere that you were allowed to bury it. For example if you own a large piece of land. So it was not easy for people to "get rid of" a horse when it was old or injured, therefor they are so often slaughtered here.
@BK: I watched the clip and I've seen many like it.

That was one of the reasons I became vegetarian and then vegan.
I kind of hate the meat industry, it's disgusting in so many ways. Another thing: If you keep lots of animals like this for food, they have to be given a lot of medicine, hormones, antibiotics and lots of other synthetic things. When you eat them you eat the stuff that has been put in them too. This scared the hell out me anyway.
(and yes I know there is unhealthy stuff on vegetables too, pesticides and things but I still find that less harmful

)
I don't judge people who eat meat no matter what kind of animal it is, but it's not for me.