So we just built a new home…6 months later I want to install smart dimmer switches a little at a time…so I am ready now and go to pull a switch off (yes I shutdown the breaker)…when I open the double gang box, both switches have ground wires attached to the switch but don’t attach to anything else…these are typical plastic electrical boxes…they are wired line in and load out which appears to be correct (I tested with the switch closed and opened)…the neutrals are pigtailed in the back of the box and the grounds are pigtailed in the back of the box (assuming they are the circuit neutrals)

Well that got my curiosity going and I opened a few more switch boxes and found that they were not grounded either

My question, is there some valid reason or part of code that allows for each individual switch to not be connected to the ground and the ground pigtailed instead??…so I am assuming with my limited knowledge that the switch is not physically grounded or is it via the pigtail???

Thanks in advance for any advice