Thai Immigration has not changed the way of operation, since 2 years a lot of people being denied entry for not having the proper coverage, nothing new. Just get your paperwork in order, I believe the person in question had over 10 years of experience and now he got denied entry.
Personaly I know this person and he has an long history entering the country under visa exempt, nothing wrong with it, but now these times coming to an end. All Thailand is asking that you get a proper visa. He can still get a Tourist Visa n enter again, but should be prepared for the 3 items.
you refer to THEM, do you mean two people sneaked pass airport Immigration and left without paying the overstay? And TWO people came back, passed Immigration and both got 60days extension. If that is true than a trip to Immigration in your area is in order.