[moonrab]

This pay monies then serve food was not the norm at least when I was young. That time not so many fanciful like scan QR order food etc. Why early days is eat first then pay monies possibly is owner dun wanna make customer not happy? Imagine I customer I go in order food then before food served you ask me for monies you think I no monies to pay after eat finish is it? Then I don't patronize liao lor. What some do is print receipt put on your table and then cross out each item as it is being served. This pattern still not foolproof as patron can eat finish run road don't pay.

Conclusion. Pay monies first then get food still the best option for owner but they risk making customers not happy don't patronize them in future. A catch-22 situation for owners indeed

Some kopitiam zhi cha already practicing it. Once completed serving order, the assistant will come for payment. 
So they don't have to monitor so many dinners. 

I think most patrons will be agreeable, since what they ordered is completed. No reason not to pay up.

Probably a few thin skin people will be offended. In business, you cannot accommodate to every customers. 

Restaurant is different, they have a door for entrance/exit with CCTV.
KOPITIAM is open to all eateries area.