First of the OP’s bias is exposed when he called CY “kosher milk”, implying that all the psaks that hold that milk undr US government regulation is kosher too are wrong.
Regarding supervision of baked goods coming into the stores, DD’s supervision is tougher than any mashgiach.They have one of the toughest franchise licsencing agreements in the business and are so sringent and focused on quality control,they have pulled franchises from operators who tried to play games.
In the end, no one is forced to accept the hashgacha and buy there.