Hi there. Your survey and findings are correct. The medicine and nasal spray you were prescribed seemed quite common and you can easily get them from the pharmacy without prescription except antibiotics and other controlled medicine like steroids. Our medical systems follow the British's NHS. But we have many private clinics with specialist doctors, family medicine doctors or general practitioners. You should have googled ENT specialist clinic and seek further treatment. The fees would be lower but waiting time could be slightly longer. You have chosen Gleneagles which is the most expensive plus a senior Specialist doctor with the 'Dato' title and you agreed to do the endoscope procedures, hence your bill would be high. Local people would not have visited this specialist doctor for a first visit on minor symptoms. However, parents here would more often bring their children to ENT or child's specialist doctors or trusted family doctor at private clinics for common cold and flu. Healthy adults would just get some medicine from the pharmacy or go to any clinics nearby.
Neighbourhood clinics are very professional and responsible... They will refer you to Specialists if necessary... Otherwise they will just provide the required treatment within the clinics , and the cost will be much lower
If not serious u cam go to clinic and if the condition is serious the clinic doctor will recommend and advice you to some specialist for further checking. As for the insurance, i saw some foreign youtubers live in malaysia they mentioned about NOMAD INSURANCE which cover outpatient claim too but i cpuld be wrong. Maybe u can do some research about it. Hope this help.
Thailand is like this .Paid 2000 bahts to see doctor for medicine (Aspirin :100 mg) And medicine is valued 200 bahts .If you can buy at shopping centre, NEVER go hospital or see the doctors .