Some do.. Some do not... Some only do it for other COMMERCIAL drivers.
Likewise,,If I flash over a trucker..Some flash marker/tail lights, some do not.
Recommendation is to listen to the principle in the following story:
Man stopped in NYC's Central park on his way home to buy a newspaper.
The vendor was the surliest person his friend (Who was walking with him) had ever met.. I mean this man had a kind word for NOBODY... The principle greeted him with a Cherry "Good Morning" and the vendor replied "What's Good About IT?" and it went downhill from there on the vendor's side.. The principle remained polite and cheerful, with the vendor getting nastier as they went.
The transaction completed.. The principle and friend left.. The principle still in good humor.. His friend ask why he was so polite Even though the vendor was anything but.
The Principle replied: I refuse to let HIM control my actions.
Be polite,, Be helpful,, Be courtious, and if the other driver is not.. Well, that is HIS problem.