how come sg mixed vegetables rice stall not same like malaysia where u can self service?

i like the malaysia type where its a big area like buffet tables with trays of cooked food, u can ownself scoop n pile them onto your rice. n then u go to cashier n they will estimate the price.

like this i can actually select 5 or 6 dishes in small quantities, instead of normal sg stall where once u hit 3 dishes your plate is kinda full.