I'm going to quote their comment

Why are Americans so afraid of charging people the cost of doing business and then get all pissy if they don't get paid what they believe to be the cost of doing business?

In this quote who is the "they" who is not being paid? What does it mean that they're "getting all pissy?"

Here's my interpretation:

1. "they" are a worker who is dependent on tips

2. "get all pissy" means to get upset, and has a negative connotation, like the person is being unreasonable by being so upset

I feel like I'm being fucked with here because this is pretty clearly, to my eyes, treating the plight of the person who was stiffed as something trivial. Treating the suffering of someone who was wronged as trivial pretty clearly to me is defending the person who wronged them.