Hey lookindown, what makes you think there hasn't been a rule that forbids holes on the beach, for the last 150 yrs.? There most certainly is. It's going to be in minutia like "alterations", "defacement", "vandalism", etc... Even if not specifically saying the word "holes". And yes, any public beach WILL have verbage that disallows "destruction" and so forth.
If you don't believe this is a logical conclusion, then you apparently have not followed any of the threads when it comes to park turf, on this subject. Because I notice that people there, feel this type verbage does indeed forbid holes. And heck, even city persons who will gladly tell you that, when you go seeking permission to detect (morphing that to apply to your question).
Hence yes: I bet you could find a city or county or state person to tell you that holes (even those from little kids) have been illegal all along.