I agree with your assessment on the extraneous questions. The purpose of which was to delay them while the computer runs their paperwork and ID, looking for warrants and bolos that match. I wouldn’t trust the speedgun numbers either.
They became argumentative only in response to the repeated questions because they knew it was a tactic and where it was headed.
Seatbelt laws require that they all be in use, not that there be enough for all occupants. Otherwise, it’s poverty discrimination essentially disallowing larger families the ability to travel.
“Seatbelt laws require that they all be in use, not that there be enough for all occupants.”
So THAT’s how the illegal alien runners on the southern border don’t get cited....