One of the reasons why most aquariums and containers for fish, turtle are made from glass or similar material is because the turtle can move out of any container, which is not large enough
They will simply overturn the container, and move out,
If they are kept on a small stool, they will also jump down and wander around as their shell will protect them. They are using their front legs to check if the area is safe for walking, however if they want to move out, they are willing to jump
It is very difficult to find a turtle who is wandering around, as they can blend with the floor, or may be hiding under the cupboard. There is a great risk that someone will stamp on them, injuring or killing them, when they are wandering around, so it is better to keep them safely.