Whistlejacket, by George Stubbs, 1762
The current European scandal over horse meat showing up in Ikea's cheap Swedish meatballs is felt most queasily in Britain, the traditional center of not eating horses. The horsemeat taboo  landscape is complicated:
Horse is commonly eaten in many countries in Europe and Asia.    It is not a generally available food in some English-speaking countries  such as the United Kingdom , Ireland , the US ,  and English Canada . It is also taboo in Argentina ,   Brazil , Israel , and among the Romani people , as well as Jewish people  the world over. Horse meat is not generally eaten in Spain  (except in the north), although the country exports horses both "on the hoof and on the hook" (i.e., live animals and slaughtered meat) for the French and Italian market. Horse meat is consumed in some North American  and Latin American  countries, and is illegal in some countries. For example, the Food Standards Code of Australia and New Zealand definition of 'meat' does not include horse.  In Tonga , horse meat is eaten nationally, and Tongan emigrees living in the United States, New Zealand and Australia have retained the taste for it, claiming Christian missionaries originally introduced it to them. 
Yet, the central thread is that the English-speaking peoples don't think much of eating horses.
I'd guess that it's because England has always been a relatively rich country, allowing the English to develop a more than purely utilitarian relationships with their horses. For example, modern thoroughbred racing emerged in 18th Century England.
I'm not sure if Whistlejacket is a direct ancestor to any current racehorses, but some of his ancestors, such as the Byerley Turk, had many descendants competing in last year's Kentucky Derby. The genealogy of thoroughbreds  is better understood than the genealogy of most people, and this helps get people to think of horses as individuals.