[@Dusksong] We'll I think [@DarkwolfX37]'s whole point is that we shouldn't have the technology to turn off their powers, or go through dimensions, etc.

I think the combination of the forcefield and an implant chip to keep them in or to kill them if they get out of hand is enough without turning off their powers. Especially since all the Mal's who are crazy powerful get executed anyway.

But I agree with everything else you said. I feel like collars have a visual appeal for some people, but it just makes more sense for them to have chips. Takes less money to make.  

Pluuuus, it stops the govt from looking like they're keeping slaves. If the govt is going through the trouble of calling it a "Training and Education Facility", there's clearly a certain image they're trying to uphold.