That's fine in theory hatwoman, but in a crowded playground, with a dog on a long lead, keeping your child away from a pet owner isn't straightforward.
My child did not go near the dog that leapt at her intentionally. She was just running from the school ramp to her mum, as any reception child would. The dog wasn't being held tightly enough on the lead and leapt at her, teeth bared (probably friendly, but certainly not perceived that way by a small child) and scratched her.
I accept that in this case the pet owner was irresponsible and not all pet owners are, but how do you tell the difference? Well, you don't. Not in a situation like this. You enforce a blanket rule that ensures the safety of the majority. And ffs, is it really so tiresome to leave your dog at home when you pick your kids up? I wouldn't light up in a playground...I wouldn't swear in a playground, I woudln't give out sweets in a playground. Because not all parents would approve of this behaviour and I respect their wishes.
If you put a thread in AIBU, you have to expect people to say yes, you are being unreasonable in whatever it is you're proposing. You asked, is it really that bad to take a well behaved dog into a playground?
Well, yes it is.
There may well be well behaved dogs, but due to the irresponsibility of some pet owners, children (like mine) who are also not deviant in their likes and dislikes, do not see them as such. They see them as a potential threat. And in a school yard, they shouldn't be forced to confront this fear.
Therefore, NO dog should be taken into a fenced/playground area and particularly not a school yard.
It may be the most placid dog in the world, but (a) dogs like that have been known to turn on a sixpence if provoked by kids (and kids do that kind of thing sometimes) and (b) if someone has had a bad experience of dogs, their fear will kick in anyway. It's not fair to put children in danger, real or perceived. And most playgrounds say that dogs shouldn't be allowed. They say that because it's a perceived risk.
I will happily respect any dog owner if they leave their dogs at home, rather than bringing them to the school playground. It's a mutual thing. You can do what you like in the privacy of your own home. You can take them to the park and let them run in the wide open spaces. But you don't take them inside fenced areas where it says 'no dogs', ie the playground areas. And you keep them out of my school yard.