To accommodate a safety lockout and your outlet detent tabs.
Nice link.... I'll learn something there, but not today I was hoping for a reason I didn't know yet.
Note: a loose detent means less pressure on the connection. Pressure has a huge effect for lowering resistance of a connection. A pressured sharp point can easily out do a sq. inch of low pressure. An interesting chart curve
@Lionelski posted:SOME The electricity from your wall outlet enters through on of those holes, and out of the other, to complete the circuit.
"That ain't right" but you aren't exactly wrong either🤔
Electrons do ride the whole surface, even the hole's.
"Magic Smoke" comes out of those too