Noone seems to have mentioned that the people who get the 600+ baht old-age payment are mostly people who have spent their lives NOT in the formal economy - piece workers, part-timers of all kinds, and of course millions of peasants in rural villages.
And they have their own 'informal' arrangements out in the villages eg My PILs (just a little older than me) have paid a few baht monthly for many years in to the village 'life insurance' (my term) fund. When they die, their 2 youngest sons (including my partner) will receive some 200,000 baht out of the village fund. (That is, if it hasn't already been stolen by the village Head Person.)