The law does say "most applications". There's probably a way to show why a slotted screw is better for an application. Or one of those weird-ass-tastic security screws used in some places for security.

But not on the sewer lids.

--
Geoff Depew - Darth Mephron
Haberdasher to Androids, Dark Lord of Sith Tech Support.
"And Remember! Google is your Friend!!"