I have seen this same type of shit on numerous occasions while shopping, dining in restaurants, and at resort type areas like Disneyworld, fairs, Six Flags, etc.......Most of the time one of two things happen. Either they appease the kyd and buy it (or give in to it) whatever it wants right away, or they actually have a discussion with the child, "gentle discipline style" as they look around as if they expect nods of approval from other customers or staff as they bargain and reason with the child, "We discussed this and agreed that it would wait until your birthday,
remember?", ....or "We talked about this and you made a choice to see the Captain Squiggle's show again instead of riding Mr Funny Peppers again", ....or "Only if you promise to go right to sleep tonight in your own bed, ok?", or, "You had the chicken nugget ala vomit cheese last time and you
promised that you would get beef fingers o' shit this time,
then you can have some dessert, ok Tubby?", and other bullshit nonsense. RARELY does anyone just say, "No, not this time", and walk away with a disappointed but quiet child.
I am of the school of thought that sometimes parents need to make the decision for the child without discussion, just say no without explanation, and that bargaining and discussions need to be done BEFORE (in private) they go to wherever it is that they are going, so that innocent people don't have to be held up in line, delayed service, or inconvenienced by their big display of "parenthood". NO ONE GIVES A SHIT that you are using some fucked up parenting technique. NO ONE CARES that you think it's cute to bargain with a 3 year old. NO ONE is interested in oohing and ahhing over your 4 y/o's apparent negotiating skills, It's BORING and it wastes my time and the time of everyone who you force to be a witness to the bullshit.