On the show COPS why is it that they have to lie when they pull someone of color over (continued)?

They always come up wit the "the reason I pulled you over was...broken taillight, swerving etc " excuse, but I just know for a fact they they follow people, especially young blacks and hispanics for a few blocks just waiting for the slightest little driving mistake so they can have an excuse to pull them over and search them. I hate it when they do that.