You couldn't build the Uber of today without significant resources, however you could indeed build the version of Uber that made them popular and got them access to those resources in a weekend. Uber started out as a black car app. They got lucky, went viral, and the founders were well connected enough to get funding to build out much of the advanced functionality you're referring to after the app already became popular.

It isn't the advanced functionality and scalability you're talking about here (that was built in reaction to its popularity) that made it popular. It was their MVP.