Why is all storage still in binary? If you could have a 3 state transistor you could store 25 times more information in a byte. 3^8/2^8. How come no ones done this? Imagine a 5 state transistor. Each byte would store 1,525 bytes of binary information.

I understand that binary transistors are easy to make, but surely someone could have made 3 or more state transistors at a similar size by now?