And I'm talking about households that literally do not have computers. There is no old hardware lying around, much less not just a keyboard & mouse, but the HDMI adapter, SD card, ability to apply the Raspbian OS image to the SD card, etc. Sure, search craigslist or similar, ask friends/family, you might get by. That's not a scalable solution for 1,000 kids in my school district that lack resources, much less the thousands more in surrounding districts. As with many technical problems, scaling is a challenge, not the single one-off solution.
that's an entirely different argument, which I agree with you on. the original argument was that it's more likely a spare keyboard is lying around than a comparatively expensive monitor (which is more prone to being repurposed)
> mouse, .. HDMI adapter, SD card, ability to apply the Raspbian OS image to the SD card
these would still be required anyway, they're not included in the price
let's allow a more realistic $80 delivered
yes, it's a great price for a great piece of kit, don't get me wrong. but if the price is still an issue (as implied by free monitor), it shouldn't be a big exaggeration to expect to find a second hand Pi4 for $40-50
Amazon.com $59.43 + free shipping (1-day w/Prime)
PiShop.us $55 + $7.95 shipping
...so $60 seems very fair including shipping, not to mention this larger keyboard model will cost at least as much to ship.