@Excal Because of the unstable nature of the ecosystem, as a result of the failing magic of this world. Yes, there are places where anomalies exist. Like in the STALKER games, they are highly volatile and dangerous, distorting physics and other oddities. They seem to appear and disappear randomly too.
And as a note, every person must have an I.T. Even the poor. Otherwise, they wouldn't be able to access even basic functions of the city, such as public terminals and even crossing certain checkpoints. And most people have been instilled fear about losing their I.T. Tampering with them is like tampering with someone's heart or brain. It's seen as taboo. And by implant, I might have insinuated that it was something easily visible to the eye. It's more like a molecular sequence embedded into their body. A sort of D.N.A.
As
@Rune_Alchemist pointed out, there is not nearly enough manpower to get rid of the bodies. And humans are known to be prone to 'failings'. So this method was devised as a way to ensure the suppression of the gene.
People who stray away from the reaches of the system, i.e. Divers, are risking the gene activating when they die. But not really, at the same time. The system is meant to monitor the gene and the I.T., but the I.T. will still activate upon death. And even if it does fail somehow, the city is not held accountable for whatever happens. They are seen as a mercenary force.
I hope that answers everything. I have been busy lately. But I think I will have time tonight to make the big post.
