[cptcobalt]

Why lethal force, and not a less-than-lethal thing, like...possibly an incapacitating gas or something?

I am not fan of law enforcement (in its current form in the US), but charitably, I figure law enforcement uses lethal force because they want/need to "win the race" of who gets shot first. But in a battle of human vs robot, the operator of the robot is afforded a bit more time & flexibility because they're, frankly, just a robot. You don't necessarily need to escalate to lethality.

Why do we have to resort to the default human impulsive tactic of "we have to kill" and not actually use the benefit that putting a non-human device in the field could bring?

[BoorishBears]

If you read the whole article, that's exactly what they're doing. The robots don't carry actual weapons, but they can carry breaching charges and tear gas. But "less-than-lethal" isn't really a thing, they can still kill people, so they're using the term lethal.