I hope that it's not too much of a drift to remark that "normalisation of deviance" is a concept that has been endorsed by EASA who, totally unnecessarily, decided that Europe's airports should be subjected to the dead hand of EASA regulation.
So a huge document was eventually produced, after many man-years of bureaucratic endeavour, which restated the ICAO Annexe 14 requirements with some minor changes to prove how valuable EASA is.
But since no airport was actually going to change anything as a result, to avoid any unpleasantness about just ignoring EASA every airport was allowed to have "allowable deviations" and carry on just as before.
That's a slight simplification, but the general principle is clear.