I don't have any hard data to add, but on the face of it this just seems wrong. Their cheese is famously good-for-price / cheap-for-quality, and I think their fresh produce is very competitive as well.
If your comparison is Whole Foods or one of the big grocery stores like Ralphs or Albertsons, sure Trader Joes looks competitive.
But if you compare it to stores that actually compete on price, it's overall much more expensive even if some items or categories are well priced. I.e. Grocery Outlet or Winco or Aldi (TJ's parent company?) or any number of ethnic grocery stores like Zion or Ranch 99 are much cheaper. YMMV but here in Southern California, there are probably a dozen different chains that compete on price that blow it out of the water.
But if you compare it to stores that actually compete on price, it's overall much more expensive even if some items or categories are well priced. I.e. Grocery Outlet or Winco or Aldi (TJ's parent company?) or any number of ethnic grocery stores like Zion or Ranch 99 are much cheaper. YMMV but here in Southern California, there are probably a dozen different chains that compete on price that blow it out of the water.