This is burying the other end of the lede: the suit is about someone who died because the car caught fire and their door couldn't be opened.

So it could be seen as an engineering shortcoming, even though the cause was someone driving drunk

Can't we sue the people who ran safety tests and regulations on the car to let it get on the road like that? Or the onus is on Tesla and this was a freak accident (manufactured wrong) they should have caught after design?

In this case, my guess is that door openings aren't regulated (unlike security belts), so it's on Tesla to design their car the sane way.