In a movie, back in the Roman Empire, or the Egypt Empire, labors were carrying stones on their head. Some pulling the cart loaded with heavy stones. There are a supervisors, royal guards, whipping them to move faster.
This is one of the very outdated safety law in Thailand that restrict the weight that each of the labor can carry. It is purely based on gender and age of the labor. Not thing related to ergonomic or manual handling safety things.
How heavy you can lift
In a third world, laboring children, pregnant women is very common. The way that government to show "I do care for your health and safety is to set up some guideline to restrict how heavy each type of the labor can carry. Not thing to do with ergonomic risk assessment. Just a number.
กฏกระทรวงกำหนดอัตราน้ำหนักที่นายจ้างให้ลูกจ้างทำงานได้ พ.ศ. 2547
