I am lucky becasue my Thai wife is ex-public servant and I am covered by her Thai social security. For me, the Thai system is much faster, more efficient and cheaper than the Australian national Medicare system. In Australia there are all sorts of co-payments, payments for prescription medicines etc. In Thailand it is all completely free (so far) and probably saves me in the order of 40,000 Baht per year for my day to day medical needs. I also have private insurance (50,000 Baht at age 66), but am yet to use.
To be honest, the Thai medical system is a big plus for me to stay in Thailand. I'm a bit nervous about throwing myself back into the system if I moved back to Australia.