Did you just make up that 140 number? To add to the other sibling comment, SCA (https://sca.coffee/) requires that water contacts the grounds at a temp of 195-205 F and that the coffee be at a temp of 175-185 up to 30 mins after brewing in order to certify home brewers:

> The SCA ensures that the brewer's carafe is appropriately sized for its designated machine and can maintain the coffee's warmth. Specifically, the brew must stay within the range of 176 °-185°F (80°-85°C) for at least 30 minutes post-brew. While retaining this warmth, the machine must never actively reheat the brew, ensuring the coffee's nuanced flavors remain intact. (from https://us.moccamaster.com/blogs/blog/certified-by-the-sca-m...)

Then you say

> Other customers had suffered similar burns, and McDonald's knew about it and did not change the policy

Again, lots of people cut their fingers off, accidentally, with knives. I don't think this means knife makers were "willfully and inevitably causing injury to random customers" because their product was too sharp.

The "official" recommendation for keeping coffee that I've seen, eg here[1], has always been around 80-85C, which translates to 176-185F.

Good home brewers, like this[2], will hold the coffee at that temperature.

[1]: https://kaffe.no/7-bud-for-god-kaffe/

[2]: https://no.moccamaster.com/products/optio

It wasn't just that the plaintiff spilled coffee on herself, it's that she spilled it while she was in her car and didn't immediately try to get it off (not blaming her, she was elderly). So yeah, I'm not surprised that spilling a very hot liquid on yourself and then sitting in it for an extended period causes severe burns.