Route taxi with white plates?

Recently returned from trip #3 - just when I thought I had the taxis all figured out, I saw a small white sedan with the usual Green Island route taxi sign on the side, but white license plates -

is this unusual?

There is no such thing as a route taxi with white plates....taxis are defined by their red plates.

He may have purchased a vehicle from a route driver with the sticker remaining on the car....