My car has it because apparently Audi Canada mandates that all their leased vehicles must. Beats me... the cost (which I know I paid) was buried in all the other upfront

costs. It is not intended to be a deterant but rather a means by which cars can more easily be tracked in the event of being stolen (if the VIN number goes missing, every window still has the same code and can be instantly identified as car "A")... likewise if any of those windows showed up somehere else (? seems strange, but what do I know?) then, again the car is instantly track-able.
I wish someone would steal my car. With this so-called "protector plus" program, not only do I get full replacement value for my car (through my insurance) but also a 'bonus' $5,000 from Protector Plus. Giddy up STI if that happens, ha ha.
In the case of the used Toyota, If this service was provided for the original owner, s/he damn-well paid for it at that time. You wouldn't pay for your windows to be tinted twice, why would you pay to have them etched twice...
...UNLESS... it's the "Protector Plus" service that refuses to keep track of the car's detail / information / registration now that it has been sold from the original owner. Perhaps the $350 this time 'round is for the 'insurance service' -- in which case... screw it, they shouldn't be able to force you into it the second time around.