This is about archival, not contract law. You can seal contracts with handshakes in Germany, too. But for certain types of records, you need to ensure longevit

This is about archival, not contract law. You can seal contracts with handshakes in Germany, too. But for certain types of records, you need to ensure longevity, and there are norms for that regarding paper, ink or even digital storage. I would assume the NARA has some thoughts about that, but on the local/state level things will probably be a lot more mixed than in most European nations. Both for different attitudes towards independence (I regret ever mentioning the advantages of a federal ID in Ohio), and experience (outside of universities, Europe is littered with more old documents).