WASHABILITY
Some paints are not washable at all, the paint will wipe off and leave noticeable marks (this is typically paints with no sheen like flat ), other paints are scrubbable and don’t only wash well but that can be scrubbed too.
If you never need to wash your walls, then a standard paint usually is adequate. And truthfully how many people wash their walls. In all my years of painting when my clients say they want a paint they can scrub, and I ask how often they wash their walls they typically say never… so… draw your own conclusions!