What makes you think I do not have children?
Let me tell you that you can always find a McDonalds, Starbucks or some such in central London.
Public urination is an offence that is committed by adults. I don't recall any children getting hit with a £50 fine.
You, parent/responsible adult are doing it wrong if you cannot factor in your kids needing to pee on a trip anywhere. -which is beside the point as this was originally about adults getting drunk and urinating in public.
A strong response because it's disgusting that people piss in the streets because they drink more than they should. That's the reason.