Cruise missile are analogous:
And they have been analogous for decades.
latest and greatest... but even the tomahawk course corrects etc.
As to land mines being banned... debatable. They're still commonly employed by all major powers. What the UN deems bad is frequently irrelevant. Law is what is enforced. And the ban on land mines is not enforced.
liability for software faults... this implies there is legal liability in war... which is generally not the case. Liability is only relevant if the winner decides to take the loser to court. If the winner commits war crimes... what are you going to do to him? Jack or shit?
As to the tech going haywire... sure. And? Any weapons system can do that. Your concern is what, a war machine going nuts and just killing lots of people indiscriminately? You think the military doesn't care if that happens? Believe me, they're the last people to take that lightly because who is likely to be near the fucking thing when it does that? Our own forces. So believe me when I say there will be all sorts of fail safes put in place to keep the thing from going nuts.
Now enemies spoofing sensor or hacking or whatever to confuse the system. Sure. That's just EW. The systems will be designed to deal with assumed level of EW threat. And as the enemy upgrades their EW we'll upgrade our ECC. That's just how weapons tech goes. One side upgrades a weapon and the other side updates armor or tactics or something to counter it. Back and forth.
I don't see your problem with using drones for area denial. What is your concern? that small children will wander into a denied area and eat a computer targeted sniper round to the face?
Mines and these drones are different in that we're not going to just leave them there. They're too expensive to do that and the have mobility so they can reposition themselves. Think of the drones like a mobile mine field. You move those behind the enemy as the anvil and then you move your primary manned force in as the hammer. Gong. I don't understand what the problem is with using the drones that way. They won't maneuver outside of their zone of operation. They'll move around to get shots or avoid counter fire or avoid getting flanked or to get close to an ally drone to provide suppression fire... etc. Whatever the tactical doctrine is... But the point is that they're not ranging around and I wouldn't suggest they be used to attack autonomously. I'd rather suggest they be used to DEFEND autonomously.
Again consider the base defense scenario. I have a mobile command center in contested territory. I am moving my forces deeper into enemy territory and I have a temporary base of operations. Drones are an excellent perimeter defense. First, if they get ambushed which is a common fate for sentries then I just lose a robot. Not a big deal. And now the enemy has revealed themselves near me and no allied soldiers were lost in the surprise. My own forces can now respond with a general awareness of what is going on limiting further allied causalities. The drones also don't get bored, tired, hungry, need to take a shit, etc... the other things sentries normally do that makes them less effective. Lets say the drones go out there, burrow into the ground a little bit with just their sensors poking out... and very very patiently... wait. Maybe the drones can sit there listening and being quite for a week or more. However long the batteries last in standby mode. And when the energy supplies get low, the drones dig themselves out of their holes, and roll back into base to be refueled and go through a maintenance cycle. A replacement drone is sent to replace that drone before it even digs itself out so there is no gap in the defenses.
Just an example. I'm not talking about unleashing autonomous drones on cities to go letting god sort the innocent from the guilty. The damn drone isn't going to be able to tell one thing from another in an environment like that. So you put the drone in simple situations where it is very obvious what is going on and you feel comfortable with the drone engaging anything that moves in that zone.