Heres how I see it.
This woman is making some extra pocket money doing this. She is using the courts 3 days a week, 12.5 hours a week. That means you have MANY MANY other days and hours that you can use the courts. So because 3 days a week you can't get on the courts at the exact time you want, your going to go and complain.... doesn't seem fair to me. OK, maybe shes signing up more in advance than she should, but she has lessons to give, she has to make sure she has the courts. My only issue with it is if shes the only "pro" on the court, how is she even using two courts at once? Thats what I would complain about.
But as I said, its only 3 out of 7 days a week, you have plenty of other times to go. You said "I don't want to have to plan in advance when to take my kids out to the courts." Why not?? I grew up playing on indoor courts, were we had to pay something like $40-$50 for one hour, and we had to make plans in advance for them. When playing outside, we had to go to the city, pay something like $2.50 to reserve the court for the hour. If we had done that, and someone else was on the court and hadn't reserved it, we would kick them off - it was our court. Personally, I just don't see the point of making a issue over this if - just get there and make your court time a week in advance as this woman does.
Personally I think that she should be barred from giving lessons to non residents and pocketing the income. The other residents PAY for the court for personal use. Maybe they can go to the community house, run a hose off of the side of the building and run a car wash for profit. Its the same thing.