Add frequent flier miles, "kickbacks" of a couple percent on credit card expenses that are reimbursed, clothing (such as suits) and commuting expenses that are not reimbursed, but uniforms (and related) that are deductible, etc. As you say it's a mishmash that doesn't have a real basis in some overarching principles.
In the US un-reimbursed business expenses are no longer federally tax deductible unless you fit in some very specific niches. That changed under TCJA in 2017 (effective 2018 tax year) IIRC. [1]
Entirely possible. Presumably most people who wear uniforms don't itemize deductions today in any case. The broader point was that people get various random perks that don't get taxed and have various expenses that don't get reimbursed/deducted.
Credit card points aren't taxable because they fall under the IRS rebate rule. They're treated like a coupon. Earning and spending frequent flyer miles is approximately equivalent, from the perspective of the IRS, to a 20% off bread coupon at your grocery store.
It doesn't change your point of course, I just find it interesting.
I expect it's one of those utterly unenforceable small-scale things that the IRS, at some point, decided to twist some logical reasoning around why it wasn't even going to try to enforce.
It never made sense, given that the entity issuing the rebate isn't the same one you're paying. Like if your employer (or really, anyone else) cut you a $1M check because you bought a $1M house from a random person, is that really not taxable income because it was a "rebate"?
The real ruling is that as long as you're not doing obvious scams and scandals with tax avoidance, the IRS doesn't really care.
So if you're getting "the equivalent" of $1k a year untaxed, the IRS yawns.
If you figure out how to run your entire salary through airline points, the IRS wakes up.
(The laws are complicated to decipher, but they basically come down to the above. The tax courts will look at things like "is this available to everyone, how much was it, etc, etc".)
And deductible for the individual is different from the company can buy this and claim it as an expense without having to also account it as salary to the employee.
The pay you get is an expense to the company, and if the company buys and maintains uniforms, likely that is also, but it is not counted as part of your salary even if you get to take the uniforms home.
And self-employment makes it all even more complicated.
