The issue is simple, everyone has their public health insurance number, if they have this number written on their mobile phone or on a bracelet, every doctor will be able to see the medical file if needed.
They can see what medicines you are taking, the examinations and surgeries you have had, etc.
Now in Europe they are gradually implementing a system regarding imaging examinations, x-rays etc. to be uploaded to a platform so that every doctor can have access. For example, a dentist asks for a panoramic x-ray, it goes into the system and every dentist has access in the future.
Everything else is useful only for someone who is abroad.