My syllabus includes several examples of actions that will result in a point being taken off a student's final grade, like coming in late or having a laptop and not sending me class notes. I basically have to write these penalties down. It would be unfair and wrong for me to apply them without proper warning, and I need to be able to apply these penalties in order to make my class run smoothly.
She thought that I would be a mean person because I discussed these penalties. But the reverse is true. The fact that I include these penalties in the syllabus, and use them as needed, is what allows me to be nice to people. If you come in to my class late, I will not be mean to you or make you feel bad or do anything negative. I will simply mark a point off your grade, politely inform you of this fact, and continue with the class.
One of the rules I live by is "Never impose an emotional penalty when you could impose a real penalty." Emotions are a sign of weakness; they are what you use to try to control people when you have no real power. I have the ability to chop points off a student's grade. I use that ability regularly, without any hint of negativity or malice, which allows me to control things without any emotional drama or bad feelings. I set a reasonable price for bad behavior and impose that price fairly.
People have remarked that public praise and private criticism is the bast way to handle people. That is probably true for close-knit groups. But when handling a class of 40 people, I find that the opposite is true. I am very nice and forgiving in private, but I smack people down in public to show that I am serious about the rules. It works very well.