Before Android came out, each vendor had their own OS. Google doesn't care about the OS, they just want a platform that will allow users to consume their servic

Before Android came out, each vendor had their own OS. Google doesn't care about the OS, they just want a platform that will allow users to consume their services. In order to convince the manufacturers that they should switch from something they completely controlled to something that another company controlled, they needed to know that it would be cheaper and still allow them to generate a strong brand loyalty. For example, HTC has the Sense UI which makes their Android phones look and feel a little different. You might think that this is a stupid waste of HTC's time, but in 2 years when you get a new phone, they want you to get an HTC, not an Android. This is critical in understanding why Google cannot tightly control Android. If the phone manufacturers see that they're losing the ability to differentiate their own brand, they'll look at other options.