It's a hard fought battle, Guy.
There was a line crew working up my street and I watched them work. When they came close to my trees, I said, "I'm an ISA certified arborist." That's all I said, but the climber turned around, walked to the truck, and took off his spikes. It was apparent they've run into people like me who values his trees.
The line crews are union, and you can tell by watching them work. There were 3 older guys (45 to 55) years old on the ground, yelling up to a young climber with instructions. It was obvious he had no formal training, and also obvious the three on the ground didn't either, even though they probably climbed for years and were now in a position of trainer.
That said, our company has hired guys from line work that were well trained and knowledgeable. So like any other tree service, there is a full range of skill levels working clearance. The pay is low and the work is boring. Clearance doesn't attract the better employees.
I tell my tree customers to maintain their trees before a line crew needs to come in, that avoids the problem of having guys like Clearance damaging them.
As for taking chips from line crews, they'll be stringy but chances are better that they won't vector disease than if you get them from a tree service. My reasoning is that line crews randomly work trees of different health, while tree services work a high percentage of dead or dying trees, doing removals. Line crews see a dead tree, they leave it. It's not growing into the wires.