The thing you are blatantly ignoring is this: standardized tests also teach children the lesson that there will be exactly one correct answer in all of life's situations, and that there will be exactly one OK method for every possible challenge faced. No exceptions.
Which is sometimes true sure. But it is frustrating working with academic "stars" who internalize this once they come to the "real world". They are focused so much on getting the "right answer" within some narrowly defined context of right, that they can't see the better solution by reinterpreting the problem or recasting the assumptions in a slightly different order. They are unable to combine bits of knowledge from different buckets, because the test questions are all neatly siloed.
For example, I've had this argument with fresh grads many, many times:
me: you need to limit your UDP packets to 512 bytes (or 8K depending on the situation).
them: but my teachers told me UDP packet size is a 16 bit integer.
me: yeah, but many stacks cut off shorter, because there is a different standard that says routers can drop packets bigger than their preferred size, the only minimum is 512 bytes.
them: my teacher told me that the packet size is a 16 bit field. Why are you talking about routers?
me: because you need to combine information to actually solve a problem?
them: whatever, I need to figure out what the bug in my code is causing these packets to be dropped.
Or -
me: hey $intern, let's figure out a few ways to solve approach this problem. expounds on the problem, lays out a few things that might work. The goal here is to try a few different techniques so we can work them into the bigger design. Any questions?
intern: no.
a few days later
intern: Hey I think i solved the problem, is this one solution right?
me: it's one way. It has some good stuff and bad stuff, but we want to try a few solutions to determine how to think about this.
intern: looks like a lost puppy but is it right?
Following conversation about multiple solutions and exploring solutions resembles "who's on first"
The biggest problem with standardized testing is there is no room for the idea that outside of school, it isn't always about doing the rote thing, the simple siloed task in front of you, but rather incorporating various bits of knowledge, about applying the bits of knowledge in ways that allow task completion for tasks that aren't extremely well defined with a pre-arranged solution.
In fact - the lack of a pre arranged solution is what defines most work outside of menial jobs. The idea that there is more than one approach or solution to something is antithetical to the core of standardized testing.
(keep in mind - that for the statistics to be meaningful, the tests can't allow for grading criterial other than "one strictly correct answer" or you end up with issues in the numbers as the result of graders being different.)