Not sure how familiar you are with the airplane industry but nothing is ever "100% due to human error" in these events. We know humans are controlling these planes and the equipment can always gets better. Usually it comes down to UX, checklists and more to have multiple stopgaps to prevent issues. Just a quick scan of the Flight 522 page shows there were in fact many UX issues like why can you take off when the pressure system is turned to manual? Forcing a manual override if so would have helped. Same alert sound was also used for "take-off configuration warning" and "cabin altitude warning", leading to the pilots making the wrong decision. Attributing Flight 522 to only human error is not what the courts did (check the "Lawsuits and criminal proceedings" section in the page you linked) so not sure why you would.
Ok, if you want to get into the details of this particular accident... it can be argued that UX issues made it easier for the pilots to make the fatal mistake they made (and the lawyers representing the victims' families of course made that argument, because going after Boeing is far more promising than going after a small airline which declared bankruptcy soon after the accident), but in the end it was still human error. Aircraft are complex systems which can't be made 100% foolproof, that's why they are flown by qualified and trained pilots who have checklists for things that have to be done before take-off, and one of them was checking the pressurization system ("the flight crew overlooked the pressurization system state on three occasions: during the pre-flight procedure, the after-start check, and the after take-off check").
...and the courts ultimately had nothing to do with it, because the suit against Boeing was settled out of court. Which is not an "admission of guilt" on the part of Boeing, just "give them some money to make this unpleasant thing go away".
I appreciate your point about nothing ever being "100% due to human error", especially in regards to air travel. I recently read "The Design of Everyday Things", a book that devotes a lot of its time to discussing this same principle. We should blame the UX wherever possible before assigning any blame to the individual.
Not sure how familiar you are with the airplane industry but nothing is ever "100% due to human error" in these events. We know humans are controlling these planes and the equipment can always gets better. Usually it comes down to UX, checklists and more to have multiple stopgaps to prevent issues. Just a quick scan of the Flight 522 page shows there were in fact many UX issues like why can you take off when the pressure system is turned to manual? Forcing a manual override if so would have helped. Same alert sound was also used for "take-off configuration warning" and "cabin altitude warning", leading to the pilots making the wrong decision. Attributing Flight 522 to only human error is not what the courts did (check the "Lawsuits and criminal proceedings" section in the page you linked) so not sure why you would.