Complete waste of money.
With a virus that has asymptomatic carriers and spreaders, the T&T system is completely pointless!
Let’s say 1 in 50 people have the virus but 1 in 3 of them have no symptoms, that’s 446,667 people walking around not knowing they have the virus. How can a T&T system compete with that? That’s nearly half a million spreaders who wouldn’t even know they needed to get a test.
A T&T system can only really work in small populations where everywhere you can possibly go to is scannable (what good is a scanning system where schools, offices, gyms, other workplaces, supermarkets etc. aren’t places you scan in?), mainly for viruses that are fully symptomatic, or when every single person in the population has regular tests.