The tailgate was replaced due to a collision but they didn’t install new taillight housings?

I haven’t had to make an insurance claim for an accident but years and years ago my parents neighbor backed into their car and left a big dent in the C-pillar (right behind the back passenger side door) and the insurance adjuster went as far as stating the trunk lid and bumper would need to be replaced even though they has no damage.

I’m surprised your insurance would reuse parts physically housed in the very tailgate that was damaged since they were likely damaged as well.

Apart from arguing with insurance about having it fixed again, my only suggestion would be replacing it yourself as it’s typically very easy. RockAuto has these listed for $60 (from TYC).