I wonder what makes the Dias Creek spouter an expert in judging

Green Creek - I wonder what makes the Dias Creek spouter an expert in judging another vehicle's speed as excessive. I also wonder how he knew the fire truck was not on urgent business. The comment that the spouter has to obey the law, everyone should, is typical of people who are jealous or spiteful because they got a ticket. If the truck was speeding, they got away with it, just like that spouter does when he speeds and there are no cops around. He should just be glad that there are people out there who volunteer to protect him.