In Boeing 787 and Airbus 350 aircrafts, more than half of the aircraft body is made of composite material. The composite structure of the fuselage does not indicate the damage when the body is contacted and damaged by the ground support equipment. That's why an airline company I’m familiar with issued a statement for the entire fleet to the ground staff indicating "do not touch the aircraft while servicing" (a no-touch policy).
How can the passenger mobile stairs be aligned safely from the ground without contacting such high aircraft passenger doors? Wouldn't it be possible for passengers to fall down from the gap between the aircraft and the mobile stairs, especially in windy weather?
What else can be done not to damage composite structured aircraft fuselage?
Jet bridges are operated just next to the point at which passengers will enter the aircraft. They have proximity sensors that tell the operator if they getting too close. And the bridge doesn't have to physically touch the aircraft as long as the gap on the walkway is small enough to not pose a danger to the passengers, it just needs to get close enough so that the end of the bridge can extend like an awning and cover the entrance. The parts that do touch the aircraft are usually made of material that will not damage the surface of the airframe.