In 2018, we (a party consisting of Thai and European citizens) visited Kew Pha Wok where we were allowed to cross the border without showing much official documentation or getting stamped. One person in our party left their Thai ID card at a Thai military post on the Thai side and we were allowed to walk to the Myanmar side.
On the Myanmar side, we were greeted by a person in military uniform with Shan State Army logos on it. The person was very friendly, wanted to pose for a picture (below, not allowed on the Thai side) and we were allowed in.
On the other side was a village where we walked around a bit and then we went back. What is the point of this crossing? Is it just for hopping over for a day's visit or can one actually cross from one country into the other legally with stamps and all?