Have you taken or worked with the SAT (or ACT) recently? Both tests have undergone changes in recent years (though not necessarily in ways that make them more difficult). The College Board, who makes the SAT, says that the math section is ~34% algebra and ~16% geometry/trig. Do you mean to say that a person can manage a decent score on the math SAT without a solid grasp of Algebra 2? That could perhaps be true, but remember that Algebra 1 includes topics as simple as finding the slope of a line (y=mx+b) and solving other single-variable linear equations. Geometry questions can be as simple as finding the area of a trapezoid. Both of those examples require some algebra and geometry knowledge, and they would be some of the easier questions a student could encounter on the SAT.
Just using my state (Ohio) as an example, students are required to pass 4 math credits, with Algebra 2/Math 3* being the only required subject. A student can't really get to Algebra 2 before they get through Algebra 1, and most math paths have students take Geometry between the two algebra years.
Sure, the "or Math 3" part of the requirement could be doing some heavy lifting, but whatever counts as Math 3 almost certainly comes after Algebra 1, as Algebra 1 is considered the first year of math taken for high school credit (pre-algebra, often taken the year prior, can't be used for high school credit).
I'm not intending to be argumentative, but it's almost certain that a student who earns a high school diploma in Ohio has "passed" classes labelled Algebra 1 and Geometry. However, going back to my first post, passing does not necessarily equal learning. They could have taken and passed a class due to a combination of completion points, endless retakes, credit recovery alternatives, and pressure on teachers from administration to massage the numbers in order to make the school's graduation rate look better.
*Yes, the requirements also allow students to use certain career tech math classes or computer science classes in place of the Algebra 2/Math 3 requirement. However, the computer science kids are likely capable of getting beyond Algebra 1 and Geometry anyway, and even a career-tech math class would likely come after a student has fulfilled their Algebra 1 requirement. Again: Algebra 1 is considered the lowest/easiest math class that counts for high school credit (save for math electives like personal finance, but students typically aren't allowed to take those until they've given at least a couple attempts to the subjects covered on state end of course exams, which in Ohio are Algebra 1 and Geometry.)