It’s magical thinking. They believe they found a legal loophole that means they’re obeying the law, because they don’t actually need things like license plates or a drivers license.

For example, they commonly believe that the law actually defines “driving” as a commercial activity, as in “to drive a herd of cattle”. So they insist that they aren’t “driving a motor vehicle”, they’re just “traveling in their conveyance”.

It’s why the poster made a point of saying they were privately traveling.