@antonmorse what you're describing usually happens as a way to unload the processing overhead of the system. The console has limited resources and executing the AI program plus the physics of all rendered cars have a certain cost, so "unloading" this real time processing for elements out of sight is quite common specially on older titles.
Back on topic, I think the adaptative AI is being marketed as a feature for new players mostly because the steps in the AI level are usually taken more rapidly when you're green. As in, a new player will perhaps increase in 15 points in the same period that a seasoned one will increase the difficulty in 2 or 3? Yeah, bullocks number but I just want to get the point across 🙃
So probably everybody will benefit from it, it's just that new and casual players will benefit the most.