Kids throwing trantrum in store? 2?

I am a parent of three. I do not give into to my children and i don't take them out of the store. For the simple fact that if i were to do that they would never learn how to act in public. I take my children to the bathroom so they won't disturb anyone if its a big fit and talk to them about what they are doing wrong until they calm down. If its a huge fit i take them to the bathroom and they get a spat on the behind with an open palm (which isn't much considering they are still in pull-ups) to get there attention and then we talk it out. Small fits they usually get a warning that they will go to the bathroom. They don't misbehave that often so when they get in trouble they act as if its something new to them. hen they do throw fits it really upsets me to see people stare like i have horrible children because they are generally good kids it makes me wonder if they have kids and if they do were there kids born perfect. It also ticks me off to see parents give into there children because i wonder if one day those are the going to be the delinquents robbing my house or bullying my children in school.There parents who leave the store completely make me wonder if there beating there children out in the parking lot.