I don't think that's very fair.
FIRSTLY, you can ALWAYS cancel the package if you want by contacting the italki team. You will get back the money that you haven't spent I believe. No problem.
Also sure, us teachers are here to make money as well as helping people. Of course if you don't learn much each time, you will keep learning for longer but you will also not continue with the same teacher, will not recommend that teacher to other students... However, there is only so much you can learn at any one time and if you are not prepared for the session or do not make the effort to give as much as you can to produce and practice then you will never learn. The teacher is a facilitator for learning. They cannot learn for you!!! (and god, sometimes how we wish we could!! ;))
Personally I think that it is a big cheek to think that people should teach you for free. Should I turn up to your job and ask you for a freebie just because I'm here and I can?! It doesn't matter if you're a teacher, a doctor, a lawyer... think about it. Please.
I teach here and make money. I learn here and spend money. Both help me grow as a person and both help my students and teachers. If my students don't feel like they are learning they know they only have to suggest other methods - each student is different and flexibility is the key to being a good teacher. If I know that I cannot help someone as much as another teacher could (maybe they are at a very basic level, want to speak with an American accent...) I will suggest an alternative teacher for them. Money is not everything. I prefer to enjoy my students' success.
Good luck with finding your favourite teacher.