Fortunately, it's the former. It's a 200+ year old nonprofit founded by a group of physicians in 1820 that developed the modern drug standards that most of the world actually relies on.
Towards the bottom of the page at Delta's careers page you'll note that Delta's headquarters in Atlanta has a Walmart Pharmacy in it. Delta is essentially signalling to its constantly moving employees that you're more likely to find a Walmart near an airport than a CVS or a Walgreens (especially in super-rural America) and that pharmacy is a constant stream of pilots and flight attendants grabbing refills on their way through.
https://www.usp.org/about/usp-convention
I will actually point out an amusing note about Walmart's pharmacy services - you find them in weird places. https://www.delta.com/us/en/careers/corporate-careers
Towards the bottom of the page at Delta's careers page you'll note that Delta's headquarters in Atlanta has a Walmart Pharmacy in it. Delta is essentially signalling to its constantly moving employees that you're more likely to find a Walmart near an airport than a CVS or a Walgreens (especially in super-rural America) and that pharmacy is a constant stream of pilots and flight attendants grabbing refills on their way through.