Because hawker centers are considered indoors. They stared at you not because they agree with the mask mandate. It's the typical sinner mindset that bad things everyone should share, good things I ownself enjoy.
Now you know why flaccid boomers like to go around asking other people's age. They cannot stand up for Singapore anymore and they hope everyone is old and hopefully flaccid like them. When lao charbo ask, they are asking on behalf of their flaccid husbands.