Though many countries have very good national health insurance policies, many prefer to go to private companies. This is because the private companies offer more options and coverage to suit your needs. Many companies also allow you to tailor make your policy and fit in all that is required for your well being.
A private provider will tie ups with a number of hospitals and doctors, thus giving you a wide range of options. The best part about this is, your regular or preferred hospital could be on that tie-ups list. Or you can always choose your provider based on the hospitals they have a tie-up with. Now that is more convenient than you going across town to consult in a government approved hospital.