Another reason not to have compulsory annuity

Any Singaporean Ah Pek/Ah Mah who owns a 3 rm flat does not need any compulsory annuity insurance. They can rent out two rooms to foreign workers/foreign talents. $150 per worker, max 8 workers or $300 per foreign talent, max 4 talents, will bring in $1,200 pm. Much much more than any annuity insurance schemes can pay. Also another reason to bring in more foreign workers and talents to occupy these flats. Now, why still insisting that Singaporeans must pay for compulsory annuity insurance?