I'm so envy with one SRJKC in KL which canteen caterer provide RM4.50 buffet style to student. Those student can pick their own food less or more portion which they feel is right. Is affordable even is B40 children.

Yep I don't see this trend in smk sk schools.
--> They haven't seen yet the win win situation canteen caterer-student, They will follow if method proven is good in allway.

But the srjkc and smkjc schools always always ask for donation
--> Head master told that they have two types of donation
1)Standard regular donation which approved in PIBG AGM.
2)Donation funding if there is new incoming project such as build up additional study room/ PC room infra/ School Hall betterment/ infra improvement etc
3)Donation when if school admin expenses Vs saving fund is insufficient - School will organize charity event (Autumn festival, CNY chap goh meh, children day
event, fun run/ sport game contest, Food carnival for school fund etc.

to clear their sins when before death
--> this one very subjective, bcos i saw many old aunty just gave the money (by scheduled) to school because their kids all doing well and the money is an extra.
some uncle/aunty aged 70~80 but still selling food tepi jalan, but they donate money to school when school ask for it. Probably they understood that only kitajagakita and conlanfirm government berat sebelah tak boleh harap.