Out-of-state plates

Could someone explain to me why the Vista buses, which are paid for by Ventura County, have Wyoming license plates?

If an average citizen drove around with out-of-state plates, they would get a citation. Yes, these are commercial vehicles and the laws are different, but the buses are marked as Vista (goventura.org), so it is not like they are going to leave the state.

Why is it that the government can get away with not paying vehicle registration to California?

- Ken Sandberg,

Simi Valley