Asimov's Three Laws were a plot device, not an actual attempt to codify ethics for artificial intelligence. They were never intended to be taken seriously outside of their fictional universe.

Their purpose was to set up conflict through an apparent paradox (robots can't harm humans but then robots harm humans) by showing the Laws failing spectacularly and exposing humanity's hubris in the face of unintended consequences.

Here's a big, long HN thread about it[0].

[0]https://news.ycombinator.com/item?id=19044387