The point is that if the trade doesn't occur, both parties lose out on what good could be and sometimes we cannot actually see the good but could value the good of the other. I'm not saying everyone should go work for bezos for free because his utility will rise. But more like in normal community interpersonal relationships. Say a small business owner wants to use some services, but cannot afford an expensive experienced person like a large business could (Say a high priced contract engineer) during a quiet period the resource goes idle and the business loses out, when both could have had some value if one would be more agreeable and say "look, I'm not working right now and sure I'll work for X% off for that reason and because I like you"
And where it fits with the commentary on minimum wage is that it technically would be illegal if that percent off dropped below minimum wage, then no trade could happen leading to vicious cycles rather than virtuous ones. The business that got its website built can make more sales and can pay more for high priced engineers. Whereas the business that cannot get a website built loses out on sales and cannot give any future work to the engineer. There's a sort of symbiosis in the health of the actors in the system and their ability to pay for generally good things.