Exactly, starting out in a garage sounds like starting out from nothing, but in reality it means that your parents have a house with a garage that they lend out

Exactly, starting out in a garage sounds like starting out from nothing, but in reality it means that your parents have a house with a garage that they lend out to you for free, where you can do whatever you want (so forget condos undergound garages), and that house is probably not very far from a large city so you have access to clients, employees and resources. You don't need your parents to be millionaires to get that, but in today's terms this is definitely upper middle class.