There are various reasons. Firstly why give a public company free advertising? Then there's the opposite problem, when a company may demand a license fee for di

There are various reasons. Firstly why give a public company free advertising? Then there's the opposite problem, when a company may demand a license fee for displaying their product in a show. Then there's legal issues such as accidentally portraying Google in a negative light and getting sued. Why bother with the hassle when you can make up your own company?