Upvote:5
Since most Americans no longer raise their own animals, or have to preserve meat for long periods because fresh meat is readily available, they no longer need to buy meat in such large quantities that an entire animal is required, so it is cut up for convenience.
Even so, you can certainly purchase whole dressed game hens, chickens, and near major holidays 25 pound turkeys, so the driving force is not really a repugnance for animal shaped food.
EDIT: Another factor that would drive customers to demand whole animal food or unprocessed food would be fear of adulteration or substitution. A can of tinned meat might be horse instead of beef, but the entire cow standing there is pretty much a cow.
In the US, these days, the national inspection and labeling rules are such that few to none worry much about a package of meat in the store being some other product besides what is stated, and wholesome.