A prick eared dog lays his ears down when petted on top of the head. Can petting on top of the head damage the ear set? Yes, I've seen it happen, but only in young dogs whose ears were not set. Just as it is easier to get a dog fit who was fit in his youth, his ear set is more reliable when the musculature is well developed in youth. Ear set depends on three things: 1. thickness of ear leather, base/orientation (placement relative to each other on the head), and musculature. The only one the owner can effect is the musculature. The other two are set at conception.
Is it guaranteed you will ruin a dog's ear set petting incorrectly? Is it guaranteed you will be killed in a wreck if you don't wear your seatbelt? In both cases you are changing your odds by taking risks.
I had a boyfriend with a crazy uncle. Said uncle would cross the 4 lane highway at the end of his drive by flooring it, figuring the faster he was across, the better his chances. Even if that meant not being able to look both ways and choose the best opportunity. He succeeded many times. Does that mean his solution was the best to meet the objective of making the crossing? If you don't care about the earset, then it doesn't matter. If you do care, you do all that you can to improve your chances of getting a good one.
I think no less of a dog with a poor earset. I just won't tend to consider him for breeding. Taping the ears does not change the genetics that caused the bad earset in the first place. The only reason for taping is cosmetics. So I don't tape. I've helped tape, and the pup hated it. Had to be redone daily because she could tear it out no matter what you did to prevent it.
If a shep's ears are not reliably erect by six months, they never will be. That's why you tape at five months if you are going to. I don't. There is no functional reason that the must be erect.
Prick ears are more prone to foreign objects and drop ears are more prone to infection. Six of one, half dozen of the other. I told my sister once Ruby had a bug in her ear. They're like satellite dishes up there. Natural bug scoopers. Sis thought I was speaking metaphorically. A good shake usually gets them out.