Hitching is never entirely safe in any country in the world, and we don't recommend it. Travellers who decide to hitch should understand that they are taking a small but potentially serious risk. People who do choose to hitch will be safer if they travel in pairs and let someone know where they are planning to go.
One extra reason to avoid hitching in Myanmar is that local drivers may not know which areas are off limits to foreigners and may unwittingly transport them into such areas. In such cases the driver will probably be punished.