"Exᴘʟᴀɪɴ ᴛᴏ ᴍᴇ, ᴛʜᴇɴ, ᴡʜʏ ᴛʜᴇ ᴘʀᴏᴛᴇᴄᴛɪᴠᴇ ʟᴀsᴇʀ ɢʀɪᴅ ɪs sᴏ… ɪɴᴇғғɪᴄɪᴇɴᴛ."
"Because you ordered me to cut costs if I wanted to keep everybody employed, and that means cutting back on things like laser detectors. We couldn't afford enough lasers for a proper grid spaced closely enough that nobody could slip through them and still keep Kevin employed - you know, the one whose kid just got diagnosed with leukemia?"
"Yᴇs, I ʀᴇᴍᴇᴍʙᴇʀ. Tʀᴀɢɪᴄ. Bᴜᴛ ᴛʜᴇ ᴀɴɢʟᴇs…?"
"Well, nobody can see the actual laser beams unless they blow some dust in the air, and even that isn't really effective and only lasts for a couple seconds. It's not like in the movies — the dust doesn't just hang around conveniently in the air and keep the lasers visible. Dust settles, that's a notable thing dust does. So we placed the lasers at — well, not random angles, but angles that an intruder's not likely to catch with a single blow off a compact, but that they are likely to catch if they're just moving through the room. I did the math, it's a whole thing. I had to make some assumptions about the median body size and agility of an intruder—"
"I sᴇᴇ. Sᴏ ᴛʜᴇ ᴏʙᴊᴇᴄᴛɪᴠᴇ ɪs—"
"Stochastic security, yeah. Do you want me to show you the math? I've got a notebook—"
"Nᴏ, ʏᴏᴜʀ ᴇxᴘʟᴀɴᴀᴛɪᴏɴ ɪs sᴜғғɪᴄɪᴇɴᴛ. Nᴏᴡ, ᴀʙᴏᴜᴛ ᴛʜᴇ ᴀɪʀ ᴠᴇɴᴛɪʟᴀᴛɪᴏɴ ᴅᴜᴄᴛs…"
"Ah, yes. Those are larger than I'd like, but they let the knife roombas move through without getting stuck."
"Yeah! I'm surprised you haven't seen them. I mean, they're not actually roombas, they're duct-cleaning robots, but Kevin said 'hey, what if we strap a knife to one of these?' and it turned out to be really effective, so we stuck knives on all of 'em. Bonus: it turns out they're great at cleaning up the blood of whoever tries to get in through the ducts."