Without regard to the morality of the matter, the only advantage of eating a cow is there is a lot to eat, compared to any other domestic animal. Sometimes this is a disadvantage, such as for a small group during hot weather. Most of the meat will spoil before it can be processed.
Modern technology has pretty much eliminated that problem, but in terms of economic input for the amount of meat produced, beef is the least efficient use of resources. In pre-modern times, a cow was a grass processing machine that provided the raw material for cheese, butter, and yogurt. Eating a cow was much the same as killing the goose that lays golden eggs. It was only when the cow was too old to produce milk, that she became food. This only applies to cows, because no one wants or needs a surplus of bulls. The fatted calf was always a young bull.
It is only the benefits of modern technology, which includes refrigeration, transportation, and most of all, intensive grain production, that allows the average American(and other nations as well) to eat beef in one form or another, practically any day of the week. The grain fed to a cow/steer in the feed lots would provide many more meals than the weight in meat they gain while waiting to be slaughtered.