If we were to copy the "best" we'd need to add a significant number of controllers, spend a huge amount on training, add more consoles and add plenty more ADS-B outlets. Care to write the cheque? Still affordable?
Not necessarily, if the correct class of airspace was used for the traffic densities with the appropriate surveillance, not a half arsed system that doesn't work, then it would be affordable. The real waste is installing surviellance that still requires procedural control, what's the point? Why install a system that gives you situational awareness but can't be used for separation? Name any ANSP that would do that. The truth is, multilat or whatever you want to call it is a massive cockup that no one has been made take responsibility for. Why hasn't Hobart and Launy got surveillance approach? The traffic densities warrant it, so what if a tower controller has to be approach rated to separate using a 3 mile radar standard.
You keep claiming it would cost next to nothing, yet the people who would be doing it say it would cost a motza.
Let someone with finance qualifications deal with that.