If they said they carry everything that is in print and commercially available, then it would be. However, they are free to pick and choose what they offer.
Further, it's an excellent business practice. It's actually the gold standard. It may not be consumer friendly, but it creates more profit which is good for the stockholders.
The fact is, a business is most profitable when it charges just enough for the least amount of product that the majority of customers will be satisfied with enough to continue to pay for it.
A certain amount of churn is expected since you can't make everyone happy. There are some people that would find faults if it were free.
However, unless that churn becomes excessive and profit continues to increase, it means the company is doing everything possible to get maximum revenue for the minimum amount of product expense. In a nutshell, a subscription model best serves a company when the customer doesn't use the product, but continues to pay for it. Health clubs thrive on this principle, as does insurance.
That doesn't mean the customer has to like it, but it won't change if people continue to pay despite being unhappy.