That may be oversimplifying it a bit. You may have seen a problem before, but you:
A) Don't know how you did on it the first time, so you may get it wrong again (in this case recognizing a problem may be a downside)
B) Have likely seen many similar problems if you took practice tests and studied books specifically designed for this exam. I actually had a question on my last test that I had seen the day before on a practice exam. Almost word for word, with the the only difference being a single dimension.
Additionally, it's unlikely they're going to repeat the same question in back to back tests. There's probably an algorithm that prevents that from happening. So at best a question may appear two or three cycles later. If you can remember specific questions from that far back, then good on you, you probably deserve the bonus point.
Think of it like this, they probably have a few hundred (maybe even a thousand) questions with lots of small variations. If they started releasing diagnostics with specific questions, that number would whittle away pretty quickly. They'd likely need to hire way more test makers to keep the pool of fresh questions up, which would increase the cost of the test even more.
Also, the lateral test seems rigged towards specific structures and areas because the ultimate goal was to eliminate the state exams in WA and CA. So to appease the strictest you needed to screw over the the others requiring the test. I can imagine a breaking point in the future, where Illinois, and Georgia, and anywhere else that decides to require this exam are forced with either allowing structural design with a PE (or just getting rid of that weird law in GA regarding which test you can take, which is dumb for many reasons), or they push back hard on NCEES and force them to soften the exam, which will likely force CA and WA back to state exams. The goal to eliminate those exams was to allow easier license comity. So it really appears like someone will need to make a hard decision, either NCEES, or the state boards. CA specifically calls this exam a "mastery" exam, so it stands as bizarre that you need it for very simple structures in some non-seismic states, but I guess that's why I'm not an administrator.