Dave, how old is your house? Pretty sure that garage style was a "feature" for new houses from the early 20th century. In this era, the Model T was changing transportation in America, and these garages seem to be "Model T sized" - like a budget-priced carriage house for your budget-priced automobile. I see a lot of these little garages at period houses around here. Seems like the idea of additional space in the garage for storage or woodworking or whatever did not become popular until the 40s or 50s, and these earlier garages had just enough room for a smallish car and entry/exit from the car.