You only need to remember the earliest days of SGK for expats - when it was supposed to be being made compulsory. The number of expats who claimed £80/month (roughly the figure quoted at that time) meant they couldn't afford to live in Turkey. I said at the time, it was incredible to learn how many people are living (in fairness often also in their later years) with no health cover whatsoever, in a foreign, non-EU country - and claiming £20 a week was absolutely beyond their means.
If not them, who do they think should pay for their heart surgery or cancer treatment?