Different people lean in different ways. If you prefer a more formal classroom style of learning then, ideally, that should be available to you. But it does cost more. Many people are willing to self-study for the exams, to save money and time. So I guess the demand for taught groundschool is relatively low, at least at the PPL level where the subjects are relatively easy.
I sympathise with your slogging through Airlaw, I struggled to learn it - my technique was to imagine how the information would be of use to me in a practical sense.