yeah that was weird. the only explanation i could think of would be that he only has hazy and blurry memories of his past, he can't remember the faces of people he knew, even his parents. only the face of Gracie was clear. he prioritized his new friend Bernie and dived in work.
usually people with memory issues try to recover it and investigate. especially if there was something as important and serious as a life taking accident that he caused.
also, he is supposed to be thousands of miles away from his home town, but he still could go back there by car in half a day
his parents' house should also still be there. that should be a huge memory trigger.
same for the site of the accident, and the prom room.