Flyn,
There's no doubt about this - driving schools and instructors offer
introductory driving lessons for free as a way to get more students who will hopefully turn into a paying customer and make them some money. However not all cheap driving lessons are not worth the while. If there aren't many driving schools in your area, then the competition will be less and the schools can charge you more money as a result. Some instructors will charge the top fees that they can get away with while more honest people will only charge what is reasonable for the driving lessons.
It's sad to hear that you and your friends did not get decent driving lessons. As I always say, it's better to go with an instructor who has been recommended by someone you know as they can vouch for the instructor's ability and worth.