I have a 3 year old whom I adore, and I am a grump about children. Parents and kids have my goodwill and understanding in most places, though.
If I have left my kid with a babysitter and am paying dearly to dine in a swanky, quiet restaurant, I will be supremely irritated to listen to another child caterwauling throughout dinner.
Children do not belong in tattoo parlors, period. My husband had the bright idea of taking our son along with him to a multi-hour tattoo appointment and still doesn't entirely get why that's a terrible idea, but he did at least listen to me and scrap that plan.
I once went to a midnight showing of an R-rated movie and was irritated to see a sleeping infant in a carrier down the row from me. I was pleasantly surprised, then, to see the parents put soundproof headphones on the little one, and loosely drape a blanket over the carrier. The babe slept straight through the movie! I have no doubt that if he had started crying, the parents would have taken him out right away.
My son is an energetic, hardheaded little scamp, and yes, it would be easy to let him misbehave and do nothing because "that's just how he is". But I don't. It takes a lot of effort to help him behave properly in public, so I kind of resent parents who sit back and do nothing while their kids misbehave.