that one time Sadie did get upset about the pop star performance (where Steven and Sadie's mom wanted her to perform on a stage) and Steven realized he fucked up, big time

he's like a little kid, and the show portrays him as such
he gets into trouble and sometimes understands what he did was wrong, usually because he sees how it affects others
so to me it makes sense he doesn't realize what he's done if he doesn't see the consequences

he's not a particularly smart kid, but he's not selfish either
he's more like a morality pet, not "main character who's always right"