Personal income tax is more restricted but still works in a similar way. For example if I need to purchase a high-vis work outfit in order to do my job, that expense is deductible.
You also need to purchase food, housing and clothes to perform your job but those expenses aren't usually deductible so I would say there's a double standard.
I would imagine most lawmakers would actually agree with you too if it wasn't difficult to distinguish bare minimum spending with nice but not absolutely necessary spending.
Where do you draw the line between, "I need clothes to function as a human being", and "I buy clothes because I'm into fashion?"
We could probably come up with some general fair-ish rules, but their effects on consumer spending might do more harm than they help.