Yes income taxs and corporate taxs are one of the lowest among first world country but what about HDB price , COE ...ect ? By the way you haven show us how $1250 enough to support a family of 4 ?
HDB 99-year BTOs are subsidized. Try buying on the resale market, where people are willing to pay a lot more for a HDB apartment with not more than 94 years on the lease.
COE prices may be high, but it is not compulsory for you to buy a car. I know of families with young kids who made do without a car for years. They are happy that they saved a ton of cash. It's the same with GST. Not happy with 7% GST, buy less stuff.
$1250 a month is manageable for a family of four. Eat at home more often, drink and smoke less, have cheap hobbies, eat less often at restaurants and pay your bills promptly to avoid late charges.