This is why a course in behavior modification should be a requirement for becoming a parent. I will admit I don't agree with spanking. If you spank your child does that mean you are a terrible person? No. But for me it is not an option for discipline. I am a fan of love and logic (natural consequence whenever it is safe to do so). I would probably glare at somebody if they pulled a stunt like that in a grocery store. There are other ways to handle tantrums, half the time it is for the attention. There is a thing in behavior modification called extinction. You take away any reinforces for a behavior (normally attentions). There are kids who will throw tantrums for the attention or to leave the place they are at. With extinction, you simply ignore it. You will experience what is called and extinction burst (the behavior will temporarily get worse), but within a surprisingly short amount of time the behavior will stop.
I do know parents who discipline their kids effectively without having to resort to spanking, etc., by setting rules, giving the child responsibilities, rewarding good behavior, and using the time-out when the rules are violated. It's unfortunate that the term "abuse" has such a broad meaning with no clear boundaries that it's often, well, abused.
I had a friend from college who went on to teach in NYC public schools and he once reported that they can't even make kids sit in the hallway when they've been disruptive (cruel punishment), and when kids get suspended they still have to come to school (also cruel punishment, plus fear they'll get arrested or killed on the streets).
My favorite story from my father's childhood is his mother's method of correcting his habit of calling his older brother a "liar". My grandmother had him write, 'I shall strike the nomenclature prevaricator from my vocabulary' 100 times. He had to tell her what it meant. If he didn't know what the words meant, he had to look it up. He never did this again! ;)
I will agree with not having a child sit in the hallway. Not because it is cruel but because as a teacher I am legally responsible for whatever happens to that child. If that child were to run away, get injured, etc. and I had them where they were not visible to me, I am guilty of neglect and breach of duty. I could be successfully sued and lose my certification.
What my district does with suspensions is a homebound tutor or classes at the juvenile center. The child is removed from the environment, but is still responsible for learning the material. This should be used as a last resort though, as a school's primary purpose is to educate, and education is difficult if the child is not present.