With the cost of space in any major city, anything that requires a workshop, working space, or significant storage space is out of the window nowadays for anyone in a major city.
When I was a teenager my side hustle was buying, fixing, and selling used cars. My dad's was the same with small fishing boats.
The story of these billion dollar companies being started in their parent's garage sounds inspirational and all, but I'd imagine less so for the kids whose parents can't afford home with a garage.