Meals for self-employed folks are not generally tax deductible. The exceptions are business entertaining (50% deductible; must have clear connection to immediate prospect of a business goal) and meals during business travel (50% deductible; you must spend a full day or more away from one's home).
Meals furnished on an employer's premises for their own convenience are not considered income to the people receiving them. Why? Tax code says so. The business can typically deduct whatever it costs to provide them, either materials and chef salaries (etc etc) or whatever they pay to the meal provider. Why? Tax code says so.
Why the disparity in treatment? "Overwhelming potential for abuse" covers most of it.
Fun fact: in Japan, while it is theoretically not allowed by the tax law, actual practice among many small businessmen (encouraged on not just a wink-and-a-nod level by the National Tax Agency) is that all or almost all personal food expenditures are business expenses. It's widely considered "one of the perks" you get for paying e.g. self-employment taxes. (In the vanishingly rare event that the NTA audits a small businessmen the discussion goes like "Why did the business pay for this meal?" "To soothe my body from the rigors of work and maintain productivity." "Approved.")
