Such policies have been in place for 3O over years, based on thorough risk assessment in our local environment. You can try your luck provided you got the guts and your luck hold. Remember that such crimes call for the death penalty if firearms are used even if its pointed at someone but not discharged. Or a long staycation at Changi with rotans to be relished. Even if no firearms or fake ones are used the mere act of threatening someone to put that person in fear of death carries an extremely heavy punitive sentence. Moreover, there are high resolution surveillance and our little red dot is so small, where can you hide. Maybe better to rob goldsmith or pawn shops, they got no guards, but then they may not have such policies