Finally looked more closely at the ingredients in the cottage cheese I was buying.
Darigold from Costo...
... a lot of "extra stuff" including preservatives.
Great Value brand from Walmart...
...same "extra stuff" and preservatives.
But look at the Daisy brand...
...only three ingredients! Cultured skim milk, cream, and salt.
Looks like Daisy is the brand I'll be buying going forward!