Of course they failed. It would only work if correctly designed and has anything about Covid been correctly designed?!NT tried that method, and failed.
The "rolling the dice" risk is there, every time you travel interstate. Nothing stopping people getting tested prior to departure.
Mind you, my personal opinion is that the simplest solution is focus on vaccinations, people who are sick and simply forget internal borders exist. The resources that have gone into these imaginary lines could have been better deployed elsewhere.