Probably not too difficult to make the app itself. To build the network of drivers to make a consistent enough service to attract users(and then more drivers to

Probably not too difficult to make the app itself. To build the network of drivers to make a consistent enough service to attract users(and then more drivers to expand further) is the tricky part. + insurance and regulation, when they started they didn’t have to deal with it as much until they did, and by then they had resources to do so.