Are most cars in Blaze and the Monster Machines purely autonomous?

In the series Blaze and the Monster Machines, the intelligent vehicles Blaze (and later Watts) have their own human drivers with which they seem to have a symbiotic Knight Rider-like relationship. We see AJ the human drive Blaze and Gabby drive Watts. The cars and their drivers communicate and work on problems together. The rest of the cars (e.g. Crusher and Pickle) never seem to have any people inside them. They are intelligent – they speak, listen, work independently, and cooperate (or compete) with other vehicles, but their windows are always shown as opaque and they never seem to interact with a driver or even indicate that they ever work with a driver.

Are most cars in Blaze purely autonomous (driver-less) vehicles, or are their drivers simply not shown on-screen because they are not important to the theme or plot?