That-Guy-Again : Everything you've cited from MDH-Talk reflects (drum-roll) : State land. And Has no bearing on city, county, Fed. or private.
And to the extent that MDHTalk has various "dire sounding" things about *some* individual cities or locations : You sometimes have to read between the lines
For example : I am looking, right now, at their page for CA . And they cite some "dire" stuff about CA lost & found laws. SURE ! Every state has "lost & found" laws (that if you ask long enough and hard enough to enough lawyers, will tell you applies to stuff we find). Yet .... seriously now..... how many of us rush to the police station to turn in rings we find ?
And though some of the cities they say require permits, the dirty-little secret in those cities is : No one can ever recall anyone being "carded". In fact, sometimes you'll hardly find anyone in those couple of city halls that knows what you're talking about or where to get one.
And despite what a first-blush reading of our state park's verbiage says, the reality is : You can hunt state parks here till you're blue in the face. As long as you're not tromping on obvious historic sensitive monuments, or waltzing over beach blankets at an archie conventions.
Thus : Sometimes you have to read between the lines.
And be aware that a lot of the stuff that MDH-talk got their info. from was (drumroll) people waltzing in, years ago, asking "Can I ?" And if a "no" got passed down, that was never actually something in codified print, it can sometimes make it onto those wonderful compendiums. And then ... decades later, everyone is sitting around asking themselves : SAYS WHO ? and WHERE IS THAT ACTUALLY WRITTEN ?
So they point to compendiums like this and say : "There it is, written right there ". But when you trace back FURTHER, to see where it's anything more than someone's commentary , sometimes you find that it's actually not codified anywhere. You might just be reading commentary.
In other words : A random whimsical "no" or "scram" does not constitute actual law (even when it makes its way onto someone's web-site list). Here's a thread on the difference between commentary vs law :
http://metaldetectingforum.com/showthread.php?t=264945