Sakura, you have a very negative view of almost everything to do with children in our society. I can only assume that you have had a whole succession of bad experiences.
I agree with those who say that we are actually very lucky in that so many restaurants, museums etc take account of the needs of children by supplying high chairs, changing rooms, toys etc. When I was a child it was incredibly rare to find a restaurant with facilities for children.
I agree that a lot of people seem to make an immediate assumption that children in a restaurant or cafe will be annoying. One of the reasons is that, in my view, what is acceptable does seem to have changed for the worse over the years. When I was a child, you tended not to witness tantrums in restaurants because children were either taken out, or not taken at all until they were old enough to behave appropriately. However, visiting restaurants was more of a treat in those days, for my family at least. There was less of an eating-out culture in the UK generally (I am talking about the late 70s and early 80s here). When my mum took me out, we went to places that were geared towards families - playgrounds, swimming, toddler groups, national trust places etc. We didn't go to cafes and restaurants - it just wasn't what mums and young children did.
Now we have much more of a cafe culture and, as mums, we have much more of a sense that we shouldn't have to change what we enjoy doing just because we have children. Unfortunately, a lot of people seem to feel that they should not have to change their lifestyle at all. When you become a parent, your family's needs and limitations change. You won't always be able to eat out when you want to. You can't have quiet time in Starbucks. It is the people who aren't willing to accept this, and insist that they have the right to do what they like and bugger everyone who doesn't like it, that gives everyone else a bad reputation.
It is not that the whole world hates parents - it is that the world has changed in the last 30 years or so, but the needs and behaviour of children has not and so many children are forced into situations where they are never going to make a good show of themselves - and a lot of the people who will be tutting will be the ones who remember 30 years ago when children were less present in certain enviroments.
On the OP specifically, YADNBU. I can't believe anyone thinks there could be any extenuating circumstances that would make "pottygate" (to borrow Emptyshell's term) acceptable.