This is true, though opening_hours=* is the antithesis of the sort of freeform key that mappers generally take a laissez-faire approach toward. I’m not surprised to see both mappers and developers expecting more consistent usage of this key. Thanks to its presentation and complexity, the opening hours specification seems a lot more airtight and unambiguous than it really is.
A similarly superficially rigorous key is phone=*. It turns out that, in some languages and regions, popular style guides or publishing standards mandate the use of en dashes, perhaps one of the reasons why 786 phone numbers contain en dashes. (There’s a particularly high concentration in the D–A–CH region, possibly due to the wiki’s stipulation of DIN 5008, though I don’t have access to the standard to be sure.)
Per Postel’s law, we could strive to make the database more consistent and developers could make their software more forgiving of syntax errors that slip through.