What makes Trader Joes Trader Joes is that they carefully curate the entire experience and having a loss of control over how they are presented to the customer is a big deal.

What if, one of the buyers transporting food improperly chills some steaks and 15 people come down with food poisoning. Then, you have the media blaring out "OVER A DOZEN PEOPLE SICKENED BY TAINTED MEAT FROM TRADER JOES"?. It doesn't matter that the media report is inaccurate, all of a sudden, you have people associating Trader Joes with unsafe food handling practices and the PR damage from one incident alone is more than any possible profit they derive from this tiny store.

So, while I understand how the practice is entirely legal, I can also see how it's a nightmare from Trader Joes perspective and how they'd rather it all go away.