the business purpose of any developers is to sell their properties, they are not in the business of trapping people.

If you get your loan approved and sales carried on, they make 20-30% profits from the sales.  Who aims to trap you with 1% if they can sell it with much higher profit?

the 20% down payment is to filter out the borderline buyers. Buyers are supposed to do a financial health check with the banks prior to placing the deposits.