The expression TIT stands for This Is Thailand and is used for things that are typically Thai. In my serie This Is Thailand (see label) here a photo taken a few years ago while driving on the highway in Thailand. In front of us were 2 pickup-trucks with people sitting in the back. Well at least 2 out of the 6 people in the last pickup truck are wearing a helmet. Not sure if they are really using it for safety or just as protecting against the cold wind, as it was about 14℃ the morning I took this photo on route 101 near Phrae.
If look good you see that also some people in the first truck are wearing a helmet. The people are probably being transported to their workplace. Mind you to sit in the back of the truck is illegal by law, but as with many things This Is Thailand as there is totally no police enforcement. A few years back the police had suddenly the idea to start law enforcement on this illegal way of transporting people, as there are many deadly accidents with this kind of transport. But there was a loud outcry of people who said "How else are we going somewhere?". And they are right, the public transport is not good upcountry. So back to the old days of "up to you".