It happens, for sure. I had an acquaintance who was a cop say that she didn't feel like dragging the dude out of his car that day, so she wrote a ticket, wrote 'refused to sign' on it, and threw it in the truck bed.

My personal opinion on whether she acted like that every time an arrest would have had to get physical aside, I bet the next officer who dealt with the dude when he had a warrant for failing to appear at court had to get physical. Just delaying the inevitable.