You’re misunderstanding the UBI, then. I’m not a supporter, but EVERYONE would get the UBI, regardless of whether they work or not.
So store employees wouldn’t lose the UBI if they work at a store for less than the UBI. They’d just (say) make $150,000 instead of $100,000 per year.
If the UBI is designed to cover housing, food, medical insurance, and basic clothing, the extra $50,000 per year would allow for better versions of those items, or extra money for travel, recreation, hobbies, etc, etc.
