It sounds like his instructor wasn't really an instructor. If I were him I'd verify his certification is even legit and not a fake.
That said, your perception of diving is based on your experience. Your experience has been under the control of dive centers.
For many of us we just dive when and how we can. Be it a walk into the ocean or from our private boats. There's no instructors or dive masters or corporations controlling things.
Once you are certified you are free to purchase tank fills and do what you want. Hell, you are free to purchase everything including a compressor and never have to get certified or use a dive shop as there's no laws that a diver has to be certified in order to buy gear or go diving on their own. At least that's the way it is in the United States.
Of course doing this would exclude you from using dive shops and dive centers for dive trips and also be pretty stupid unless you actually got training.
I suffer from these charlatans who present themselves as scuba, or free diving, instructors and they aren't certified instructors or even certified divers here in Libya. There are SO many of them here causing harm and injuries to the public.