If you give them a free item just to increase your tip, isn't this ethically the same as stealing from the company? You're converting an asset of the company into dollars in your pocket.
I used to work with a sales guy who would make sales that cost the company more than the final sale brought in. Spend $12k to make a $10k sale? Made sense to him... because he got a commission on it.
As I state above, practically all restaurants run a "comp[limentary] tab", giving free items is extremely standard. All items are marked on the comp tab. Senior servers/bartenders can run their own comp tab, but most staff has to ask management. This is factored into all costs and is used to encourage repeat customers. A repeat customer and good word of mouth is worth far more than a free dessert.
There are many misconceptions about the industry from outsiders. It seems to be making people mad, but this is how the industry works.
I used to work with a sales guy who would make sales that cost the company more than the final sale brought in. Spend $12k to make a $10k sale? Made sense to him... because he got a commission on it.