The interesting thing I've noticed is that opening a new credit account often doesn't actually get that information on your credit report. It sometimes only shows up after you've made the first payment (either loan or credit card). I wonder if that's why the system dings you for too many hard credit inquiries. I agree with you that there's no reason why this couldn't be fixed, though.
And there are obviously better ways to prevent "double spend," like reporting the new loan being granted, which actually should reduce the credit score due to the new debt. It's not as if we can't make computers capable of updating this information in real time.