Uber built its network city by city and a competitor could do likewise. As others have pointed out, most rides are local - if you live in Dallas, TX, you probab

Uber built its network city by city and a competitor could do likewise. As others have pointed out, most rides are local - if you live in Dallas, TX, you probably require rides mostly in Dallas, TX. If a hypothetically better (in some way) competitor came along that only served Dallas, you might be interested in trying it out. So a competitor could just focus on Dallas to start out, raising enough capital to hire enough initial drivers for acceptable wait times in Dallas only. Once Dallas was successful, they could then go on to other cities. This is unlike a website such as Ebay, which truly becomes stronger and stronger due to national and international network effects, not just local ones. If a user selling the beanie babies you want is in Atlanta, having them shipped to Dallas is hardly more difficult than having them shipped within Dallas itself. So that Atlanta user has increased the utility of Ebay to you.