It's not just "centralized system watching every payment you make", but also a possibility that it could veto your payment.
The crude option is when 'undesirable' citizens will not be given credit cards, or if all their cards 'accidentally' stop functioning the same day to teach them a lesson. When no shop sells you food for money, your options are to beg, steal, or starve.
A more sophisticated option could be 'intelligent' credit cards that only allow you to buy approved stuff (otherwise the payment will fail); with the approval being general, or individual for each citizens, or depending on social class or whatever. This wouldn't happen overnight, but we can get there gradually... it may start by politically acceptable stuff like "you can't buy alcohol or guns using welfare money" and progress slowly.
When China starts going cashless we will get a look at exactly this scenario since it will very likely link with their citizenship score which is already implemented.
The crude option is when 'undesirable' citizens will not be given credit cards, or if all their cards 'accidentally' stop functioning the same day to teach them a lesson. When no shop sells you food for money, your options are to beg, steal, or starve.
A more sophisticated option could be 'intelligent' credit cards that only allow you to buy approved stuff (otherwise the payment will fail); with the approval being general, or individual for each citizens, or depending on social class or whatever. This wouldn't happen overnight, but we can get there gradually... it may start by politically acceptable stuff like "you can't buy alcohol or guns using welfare money" and progress slowly.