You asked: “the age when a child can say the name of a letter that’s shown to him/her, or can find & point to a letter when asked to do so (e.g., “Where’s the B?”).”
I told you that they can do so when they are taught to do so. They cannot eat with a fork until they are handed a fork and shown what it is and what to do with it. Similarly, they cannot know what “B” is until they are taught what it is. That is the way it is. It will not change, however much you protest. A child cannot acquire knowledge without being introduced to it.
If you wish to know when a child acquires the cognitive ability to learn something, ask that question. But that is not the question that you asked.
If you go on about how something is not answering your question as asked when it is answering your question if you stop protesting long enough to think about it, the problem lies with you and not the answer.
I never once mentioned anything about standardized tests. I only mentioned the age requirements for starting school because it is relevant to the question and the age at which children can be expected to know something.
Again, if you choose not to accept a perfectly valid answer, maybe the problem isn’t with the answer.
Disclaimer: avvooooooo holds a B.S. in Consumer Journalism. A large part of that degree, the “consumer” half, was satisfied by completing a large number of courses in Child and Family Development. avvooooooo is qualified to answer questions as asked about child development by virtue of her years of study in that area.