But that interpretation has ridiculously easy loopholes - why not just reduce my salary by $10K and give me a $10K company-managed Amazon budget for personal expenses? Why not just let the company book my personal vacation travel via payroll deduction? Why not have the company rent my apartment and sublet it to me? etc.

I'm coming at this from the position that the law must say, if you're giving a person access to a cash spending account that lets them buy things for themselves but not giving them the cash directly, that still counts as income. Is that true? If it's not true, why isn't everyone taking advantage of the loophole? If it is, why is lunch a special case?