The parent commenter meant that the tips are being "stolen" by the employer by an equal subtraction from their wage up to a given amount (the point where the wage + tips surpasses minimum wage.) Sort of like how an advance works in publishing: your revenue is "stolen" by an equal subtraction from your royalties up to the total amount of the advance.

A tip, in the classical sense, is expected to be something that the person you're tipping gets to keep in addition to their wage.

A minimum wage isn't supposed to guarantee a minimum level of welfare (that's what direct-transfer welfare programs are for); it's supposed to guarantee a minimum proportion between labor-in and compensation-out.

In fact, think of the alternative case: it would piss most people off to realize that giving $20 to a person on welfare, means that—if the recipient is honest—the government will subtract that same amount from their welfare check for that month.

That's the way that system is supposed to work, and people still find it unjust. So why don't they find it unjust when it's a system (minimum wage) that's not supposed to keep people "at level", but rather to increase their compensation as they provide more labor?

I agree. Tips should be unknown to the employer. This can readily be done even with card transactions; staff usually swipe a card or enter a PIN anyway to use the POS system.

One of my biggest hesitations with tipping in places where it is unexpected, like a muffin shop in the OP, is whether the tip goes straight to the employee whose performance I tipped for, split among all staff indiscriminately, or more sinister straight to the employer.