It's a bit of a chicken and egg problem. Hardware vendors won't support VP9 until it has some usage, and it won't get usage until it has hardware support. VP9

It's a bit of a chicken and egg problem. Hardware vendors won't support VP9 until it has some usage, and it won't get usage until it has hardware support. VP9 has some serious space savings, so it's extremely beneficial for Google to use it when possible, and many users will appreciate faster loading video at a higher quality. Unfortunately they can't know when you'd prefer to have a more efficient decoding experience, so they rank their codecs and use the "highest" one available.