If you prefer a different phrasing, if the back office is empty, they might as well close the immigration desks as they won't be able to do their work. (obviously "back office" can take any physical form but in the sense of people not front facing and doing required additional checks, available for secondary etc).

I also disagree with the portrayal of ZA here. It's by no means perfect, but quite frankly, by African standards, it's vastly more organised than most other countries. If you think ZA admin is on the brink of collapse, try DRC, Niger, Chad, or Erythrea for comparison (I could have picked many others).