Where have all the taxis gone?

Remember the old taxis that were replaced by the new, green ones overnight? Well, just as quickly as they appeared, they have now disappeared. They are just gone. It's the weirdest thing, as they were all new, and definitely meant for Beibei, with slogans of protecting the towns environment on the rear windows.

And now, not one is to be seen. Instead the old white ones are back on the streets.