the helicopter in the air isn't scanning with IR for grow ops. it's in the air as air support probably b/c you don't live in a great area of town...
too expensive and not worth it. i'd be more scared of a random van parked down the street than of a helicopter scannign rooftops....
what they do use is strong arm tactics. charge who they think looks like a putz with the harshest crime they can get away with, in order to scare them into flipping.
you ever seen the show DEA??? i mean, of course it would make great tv to ride along a military style air campaign scanning the rooftops, very dramatic scenes... but they just don't do it....
they scare idiots into turnign somebody in.... snitches.... assholes...