For a full explanation please see this article.
In short, the Medicare rebate (amount paid by the government) has been frozen for many years and no longer covers the cost for GPs to provide you with the service. Therefore most GPs charge a ‘Gap’ fee to cover the rest of the cost. Bulk Billing doctors are able to just charge the Medicare rebate by seeing more patients for shorter time.
GPs provide comprehensive care from ‘cradle-to-grave’ and get to know you. This has been shown to result in better outcomes and reduce hospital admissions. Because they fully understand your entire medical history they can best treat one medical condition in conjunction with others. A GP’s referral is usually required to see hospital specialists.
GPs are specially trained in the full breadth of conditions encountered in the General Practice environment. They can diagnose and treat the large majority of medical issues presented to them. Sometimes you will need more specialised care in a specific area and they can refer you to a Non-GP Consultant for that purpose.
GP stands for General Practitioner. They are also known elsewhere as Family Doctors or Primary Care Physicians.