Next, we can put them at police stations so that riots can't overwhelm them!
Then, we can put them at schoolyards so that pedophiles can't abduct children!
Then, we can install them at the openings of sealed communities to keep the 'undesirables' out!
THEN, we can start putting them on each city block of the inner city to control crime there and keep people who don't live there out!
Finally, when they're installed everywhere, we can turn them around.... so that they keep us all in.
....oh.