The problem with corps was that they had the resources to buy just about any kind of contact or informant that might suit their purposes: cops, hustlers, gangs, whole city blocks, entire governments. You couldn't evade power like that forever. Something had to give. Either the corp eventually decided you weren't worth the effort or the nuyen anymore, or it got you, grabbed you by the cojones and made you dance however it wanted, then dropped you down the nearest garbage chute.