Then why not just have a flyer do it on his/her own? I don't really see a need for them to bring along a groundwalker with them. Also, the groundwalker would just weigh them down, forcing them to flap harder and exert more energy. It wouldn't be really efficient for the flyers to scout by carrying a groundwalker with them.
An example would be the 12th movie, when Petrie was holding onto Guido. I imagine Guido wasn't very heavy, since he's a glider and would need to be light enough to stay off the ground. Petrie tired out pretty quickly just trying to hold Guido up.
A flying creature cannot hold something too heavy because it interferes with their flight. They have to remain light in order to get off the ground. The heavier they weigh (or the heavier the object they carry is), the harder they have to work their wings to stay aloft.