In the world of Blade Runner, replicants are artificial beings that are virtually identical to human beings in every way, with the exception of their lack of emotions and shorter lifespans. Despite being illegal on Earth, replicants are often used as slave labor in off-world colonies.
In the original Blade Runner movie, the protagonist, Rick Deckard, is a “blade runner,” a law enforcement officer whose job is to “retire,” or kill, rogue replicants that have escaped and returned to Earth.
There are several reasons why blade runners are tasked with killing replicants in the Blade Runner universe.
First and foremost, replicants are illegal on Earth, and so killing them is simply a matter of enforcing the law.
Secondly, replicants are seen as a threat to society because of their lack of emotions and their superhuman physical abilities. Without the ability to feel empathy or compassion, replicants could potentially become dangerous or pose a risk to humans.
Finally, the use of replicants as slave labor is a controversial and ethically dubious practice, and many people view the creation and use of replicants as a form of exploitation. As such, eliminating replicants is seen as a way to fight against this exploitation and oppression.
In the end, blade runners kill replicants in Blade Runner because they are seen as a threat to society and a violation of the law, and their elimination is a way to protect humanity and uphold ethical values.