Public transport easing restrictions as of today
This is more applicable to people in Bangkok than other parts of the country since Bangkok is the only part of the country that has a subway or skytrain system and with good reason since there are more than 10 million people living in that city.
I live in Chiang Mai and public transport is not used on a very high level as it seems that everyone has their own transport. As you might be able to imagine trying to drive your own vehicle in a city as densely populated as Bangkok can be rather counter-productive.
I've been on the MRT (underground) and the BTS (skytrain) on many occassions in Bangkok because it is simply the best way of getting around. Bangkok is incredibly prone to traffic jams and even gridlock and can be a very frustrating experience. I imagine that social distancing on these methods of transport was probably pretty close to impossible and based on what I know about how adherent to laws or rules people are in this country, I would imagine that they were probably not observed or enforced because people need to get to where they are going and waiting around in the intense heat of an outdoor platform such as exist on the BTS was going to be too much to ask of people.
Some additional information on this release from the MRT and also some insider information is that temperature checks are meant to be taking place at the entrances of the stations but there are reports of when it gets too busy during peak hours that the testing doesn't happen. In theory, if someone's temperature is above a normal amount they will not be let on the train.
The guidelines about where to sit and stand on the cars are simply recommendations, it remains to be seen if anyone will adhere to this, particularly during peak operating times. I know that in many situations I have been on these trains and people were packed in like sardines. It remains to be seen if anyone is worried enough about a near eradicated virus (in Thailand) to be concerned enough to follow the guidelines.
Also, i have heard reports that the AOT QR-code scanning app that they say you must use before getting on the train and after alighting (for contact tracing) has sporadic functionality and in many locations, including an airport that I was at today, they weren't using / requiring it at all. This is actually quite common for Thailand every time they attempt to use some sort of massive technology-driven anything as they tend to almost always get scrapped because they don't actually work.
All in all this is great news for people who have the misfortune of living in one of the world's most densely populated cities because getting around without the trains is an absolute nightmare in Bangkok.