From Earth, you want to pick something up from the surface of the moon. Using a joystick, you control a grabber — but you keep missing. It's the delay: It takes light nearly three seconds to get to the Moon and back, and the control signal even longer.
The big picture: This is a fundamental, insurmountable hurdle to moving stuff around in space if you're not there. The farther you are from Earth, the longer the communications delay — nothing, after all, moves faster than light.