I am a physician. I know that sometimes it is difficult to get the needle into the vein. I have had my own veins missed, and I have missed some myself on the first--or maybe even the second--try. As a general rule, the person who has been finding veins for a long time is the best at doing it right on the first try. It might be someone who has been trained only to do that.
I have never known anyone to assault or inflict pain on a patient intentionally. If I did, I would not tolerate it under any circumstances.
I have fired only two people, a man and a woman, both for faking lab tests in separate incidents. As soon as I proved that they had done this, I fired them on the spot.
I will say that the nurse who did that was grinning. Even after I yelped, it was weird. And the whole squeezing the bag - really never had that happen ever before. There was a lot more to that whole morning that was very peculiar. I honestly wonder if they thought I was someone else.
I HAVE had a few really rough blood draws. One in particular, oh man! But it was clear that that woman was trying her best, she was so careful, but her best was very bad, LOL. It felt like she was drilling a screw into my arm.