Why do so many drivers in USA briefly stop at Green Arrow Right Turn lights?

There is nowhere in America where you are supposed to stop at a Green Arrow right if you are turning the direction of the arrow.
And yet, a huge percentage of drivers tend to stop, look both ways, and then go…. behaving as if it’s a Red Arrow Light.
Why are they doing this?
You never see people stop and look both ways on a normal Green Light. So why would anyone do it on a Green Right Arrow Light?
Do they think they are being ‘safe’? Are they oblivious to the danger they are causing to people behind them?