The cost absolutely matters. If something costs tens of thousands of € per month for a long time then it will either not be approved or will be used very rarely. The cost is not irrelevant because the insurance does not have infinite money. They need to decide which cures, medicines, operations they fund. They can spend 1000€ to cure 100 people of something or to spend 100k to maybe cure someone with an experimental treatment.

This is one of the issues with the modern cancer cures, thst they are very specific to the cancer, the patient, need one off lab work for each patient and this makes them very expensive and not affordable to many. Despite having public healthcare the managers of it still need to decide what to spend their limited funds on.