That one is an old roll stamped model. I'm guessing the OP was laser etched? Dunno if that'd make a difference but it may factor in for the investigation as for the time period it was manufactured.
Yah it's a roll stamper, but it also has the dreaded cutouts!!!!!! KA-BAR switched to the laser stamp to mitigate any potential stresses due to the stamping process.
On another note, the break on OP's 2 is right along the temper line (or where it normally is) or where the harder blade meets the less hard tang. There was some discussion previously about the pros/cons of this method. It's supposed to make the tang more springy to avoid these breaks.
So the question might be, is the issue a mishap with the zone hardening, or the cut outs? Maybe both?
Furthermore, I really don't think there is some dreaded conspiracy with KA-BAR and their cutouts/heat treat, but probably a few outliers that get distilled and presented onto Bladeforums. If there was a major issue, KA-BAR would fix it.
People said the coating wore off too quickly, KA-BAR changed it.
Issues with sheaths dulling knives, KA-BAR fixed it, and then even changed the BK11/14/24 sheaths to increase their retention after changing the sheath formula.
Potential stress areas with roll stamping, KA-BAR switched to laser stamps.
People didn't like the sk5 Taiwanese blades, KA-BAR brought them to the US in 1095cv.
They are a knife company trying to make money that's true, but they do listen to their customers, and I have only seen them go above and beyond while simultaneously trying to provide a high quality product at a decent price.