Smoking sections in coffee shops do not have physical partitions to prevent cigarette smoke from dissipating to non smoking areas.  Cigarette smoke is proven to cause lung damage.

Non-smoking customers and food stall workers become involuntary, passive smokers.  Unless they opt out of eating or working at coffee shops, they have no choice but to breathe in toxins that would cause lung diseases.  

Why should smokers be allowed to have their masks off after eating?  Not only that,  they are allowed to pollute the air, which is already full  of harmful micro particles from cooking fumes  and steam.  On rainy days, it's  even worse when blinds are lowered to keep out rain.  The place becomes an enclosed space, trapping cigarette  smoke within.  At times, when smokers occupy all seats in their section, there's no escape from the smoke.  This is worse than breaking the mask off rule and social distancing  rule.

Coffee shops serve a varied strata of the population.  Most of HDB dwellers patronise coffee shops.  Eighty percent of the population live in HDB flats.

In the current Covid pandemic, it's only thoughtful and wise to enforce the ban.  I urge the policy makers to take action without further delay.