Well, they were hardly flying before they got to the carpark. Maybe they were sailing? Or walking with cars attached to them? That isn't heresay that they were driving on the road first, that's common sense.
Also, there's a major difference between law abiding and "awkward Aspie manner of abiding laws". The former can do it without pissing many people off. The latter takes the laws literally and awkwardly abides them, causing more harm than good. For example, going 20mph on a 60mph motorway because they see that as a sure fire way to not get in trouble. Another example would be to not download stuff off torrent websites because they see it as "strictly against the law", even though it's extremely hard to enforce piracy laws online.
I'm sure Trigger will explain, so we will see if my assumption that it was caused by his slow driving is correct. As for links, look them up yourself.