I have noticed in a few different houses in Oklahoma that 20 amp breakers are used, but all of the outlets and switches only seem to be rated for 15 amps. This goes against everything I know to be proper and safe. The wire used is 12 gauge, so at least that is fine.
I have started to replace all of the switches and outlets with the decorative switches (the rectangular ones) and have found it very difficult to find switches that are rated for 20 amps. As for the outlets, I have can find them rated for 20 amps, but not in the 10 packs that I see for the 15 amp versions. To be clear I am not speaking about the shape of the plug, rather I am talking about the rating of the internal components of the outlet.
Is there something about electrical code that I am missing?
If it is a single receptacle on a 20 Amp circuit, it must be a 20 Amp receptacle (aside from the 2 exceptions). If there are multiple receptacles on a 20 Amp circuit, the receptacles can be either 15 or 20 Amp (aside from the exceptions).
This is to allow You to have multiple devices plugged in drawing less than 15 Amps each, but the total draw on the circuit may be greater than 15 Amps.
Keep in mind that NEC defines a receptacle as follows.
So a duplex receptacle would be considered two receptacles, according to this definition. Which means you can install a single 15 Amp duplex receptacle on a 20 ampere circuit, without violating this code.