They are taken simply because a team is patrolling the area with a tow-away vehicle.
Would it not be better to double, or even triple, the number of tow-away teams, given the high incidence of untaxed cars in the capital?
Is it not better to have more tow-away vehicles to lift cars and remove them?
For that reason we have heard much about parking fines and tow-away fines.
Conversely, vehicles should only be towed away when they are in fact causing an obstruction; otherwise, the tow-away trucks more often than not cause more problems than they cure.
Of course, the tow-away enforcement laws at the moment can do just that, so your vehicle might have gone if it had been there too long.
Tow-away zones should be extended to all cities and should become the normal way of dealing with the illegal and selfish blocking of public highways.