I have a lot of sympathy for parents in public. I do. But if your attitude is that a four year old is just going to explore a table-service restaurant, here other people have food and drink and knives on their tables, and servers are carrying trays?
But this isn't even trying.
This includes climbing a store display, enforcing a safety barrier at a roadside, zoo, by the water, etc.
And it includes "exploring" restaurant aisle.
When you've got a partner there and you have one young child between you, it's not *fun* to interrupt your meal so that one of you can take the child outside for a bit.
But it's what you do, if you go there.
They have to make a snap decision about talking to or even touching a strange child.