In Europe, yes. In North America there was a time when most families had a horse. That's why we never got in the habit of eating them.
To answer the OP's question, everything horses need was cheaper back then because land was cheaper.
Good Lord, the RARAs and PETA folks must love you! You believe every bit of bunk they throw your way.
Up until the 1970s, horse meat was readily available to the American consumer, and it was in pet food until the early 1980s. So much for Americans 'never getting in the habit' of eating horse meat.
It's only been recently that Americans have taken it off their menus, and for some reason have relegated horses as being 'better' and 'more noble' than other livestock, which is anthropomorphizing poppycock.
The pioneers used oxen, NOT horses. Horses were far too delicate and expensive to be of any real value unless they had the means, just like today, to throw money into them. Plus, they couldn't afford to get sentimental over livestock. If it got hurt, it was slaughtered for food.