There are a lot of different types of plugs and sockets. The ostentatious reason is to keep people from plugging the wrong things into sockets. I sometimes suspect the real reason behind some of the variations is commercial competition. Greed.
The reason I say greed is the cause is there are some cases of incompatibility that defy safety logic. I see this in the conduit as well. I’ve got two right angle access boxes I just installed that have different covers and are of slightly different sizes. Standardization people! This is something that has been done for a long time so I would expect them to have worked out their differences by now.
Outdoors: 0°F/-9°F Sunny
Tiny Cottage: 63°F/56°F
Daily Spark: Flours are like potato chips. Nobody ever buys just one flour.