The stewards decided to turn a blind eye to the violations of the Mercedes team

This is a direct violation of Article 34.13, and is usually punishable. However, the stewards took into account the fact that this time the Mercedes team was not the only one who violated the established sports regulations. Other mechanics also worked on cars without helmets, goggles or other required equipment. 

The stewards decided to turn a blind eye to this fact because such violations have almost become a tradition. Lifting the car and installing cooling fans for the brakes has been done without glasses or helmets for many years. The judges decided that it would be inhumane to punish one team, because the rest were also breaking the rules. It’s just that in this particular case, the Mercedes team violation of this rule was seen most clearly. No one will benefit from such a punishment; the mechanics will continue to work the old fashioned way, hoping that they will not be caught violating them. "Mercedes" forgiven, but the stewards contacted the FIA to review the rules. Perhaps the organization will still hear the judges and change the standards.