Most of the problems of coding interviews can be solved by good reference checking. Code problems in isolation will never expose how a developer will do when faced with real-world issues, users, QA, and teammates.
Why are people so afraid to pick up the phone and talk to references? I'm always happy to give out my references, and always delighted to talk about the good devs I've worked with, with specifics about what they've done.
Standardized tests don't work for schools and don't work for jobs.