Answer:
Balance and the sheer amount of coding to do those things
Step-by-step explanation:
For walking, balance is a huge issue in the robot building world. Often times the code is fine, yet, the robot is off balance making it impossible to walk. Although, nowadays it's easier for builders to create a robot that works. For instance the AntBot takes a huge amount of coding and physics to work correctly.
Although folding towels takes less physics, it does take a great deal of coding. To create do something like this, the robot would have to have an AI that figures out the length of the towel and find the best way to fold it.