Well, since she hasn't been paying that $120 licensing fee, I imagine her overhead is pretty low.
On the other hand, lemons are at least 50 cents apiece in most supermarkets. Hell, even at Costco a 5-pound bag is $5.50, and that's for maybe 14 lemons at most.
When I make fresh lemonade, I use the juice of one entire lemon per (big) glass. So if this girl is REALLY selling lemonade for 50 cents a glass either (a) it's not the REAL stuff, made fresh, or (b) she's watering down her product. So, sounds like she needs some competition to keep the public happy. And fair competition means she should be paying the same fees that any other lemonade vendor has to pay.