What if you could steal items from shops when the shopkeeper cannot see you, with a chance of failure, of course? Attnam shops would require invisiblity and high Dex to pull this off, but Merka and his guards can see invisible, so you would need a different tactics or be infra-invisible to steal from him.
There should always be a chance you make some sound when stealing even when they cannot see you, so no 100% stealing. It could be a high risk, high reward way of getting items, because angering the shopkeepers is quite deadly.