The tests don't not work (I believe that within the middle of bell-curve they accomplish their goal well), but at the extremes they are prone to gamification, especially to those in the know. For example, the pre-2017 SAT had some well known (and some lesser known) tricks that you would only know by studying the test, rather than the material:

- ALL sections (and sub-sections) have questions that strictly increase in difficulty / projected "miss-rate" as time goes on. This is to keep test takers from coming back to answers they're unsure about but may themselves know how to solve -- so if you find yourself struggling with questions in a row, it's better to stop and go back rather than miss out on what you may already know trying to solve questions that you don't. For the reading section, the scale is scoped to each passage. For the vocab section, where there are 3 sections (vocab, grammar, and multiple-choice fill in the blank), the scale is scoped to each subsection. For the math section, it is scoped to the whole thing.

- The "Free Section" (e.g. the one that doesn't count toward your score, which instructors tell you before you start that section, so you can use it as a break if you wish) is usually section 4 or 5 of the test, to help plan your breaks. Some students, not previously-knowing or confused that the "free section" is ungraded, still take it thinking there must be a penalty of some sort.

- The word "equivocal" is tested within the SAT Vocab in around 60% of tests. Unequivocally, these questions have some of the highest wrong-rates of any question on the test.

- Within the grammar questions, Choice (e) "None of the above" is 99% of the time NEVER the answer. This is one of the most certain things on the test.

- The math questions will usually have (1) answer that is an outlier. 95% of the time, this is not the correct answer; (2) will be similar to the correct answer in different ways; and (1) will be the correct answer (e.g., say you're supposed to subtract "x" by 5 to get to the real answer. The obviously fake one might be multiplied by 5. One of the slightly-wrong answers might have 5 added rather than subtracted, another might just be off by 1). If you're ever in doubt, you can drastically increase your chances at guessing on a question by picking the question "most similar" to all of the others -- something like 65% chance, rather than 25% in the naive case.

- Again for math questions -- particularly the "word riddle" type ones -- the SAT will generally purposely pick questions that could have multiple seemingly-correct questions if you plug in 1, 2, 5, or 10 for the variables. 3 is almost always a safe bet, though I particularly liked to choose 7, because who thinks you'd ever choose to plug in 7.

- The essay is funny. Per the SAT's own published rules, they are not graded on fact at all; purely rhetoric, vocabulary choice, and clarity. All of the prompts also usually include a historical figure or event of some sort -- you don't need to know anything about them other than what the prompt tells you, but a well-known and easy way to win points with the graders is to make up a fake quote from someone adjacent to the event / historical figure as a hook: e.g. "Disconsolate upon hearing the tragedy of [EVENT X], [FIGURE Y]'s au pair journaled 'His life was short, but his memory will last forever'. Previously unknown to historians until then, Y's au pair embodied Y's belief that [SOMETHING FROM THE PROMPT]. [then THESIS STATEMENT on 3rd or 4th sentence, always]." (this is an objectively wrong and terrible sentence that I would hate to read in any other context. This is, however, similar to the SAT's example of a top-tier intro).

This is just the tip of the iceberg, too. It's a very predictable format and pattern (it has to be, as it's given multiple times during the same academic year; tests must be similar, lest one session of test takers do statistically significantly better than an equally-talented group which takes the test a month later)

So yes, while I believe the SAT does attempt to test for knowledge, it's that same pursuit of a bell curve that makes it easily gamifiable for those who know the test and not the material -- who are, once again, usually already the wealthy and connected.