That's interesting -- can you cite an example of when there was a national US flu vaccine mandate? What about a local mandate?
IIRC, there have not been federal or local government flu mandates although there were local government mandates for things like smallpox in school kids (but not for the entire population).
For example, here is a 2009 policy position from OSHA saying that it does not mandate flu vaccines[1]:
However, although OSHA does not specifically require employees to take the vaccines, an employer may do so.
But if I missed an example of a historical flu mandate, I'd love to hear it.
I did a very rudimentary google search and see that the federal government requires a bunch of vaccines including influenza and Covid-19[1] for obtaining a visa. The CDC publishes a "menu" of state hospital vaccination laws[2]. Those sound like they both clearly fit "many contexts in the US that required a flu vaccine" the parent mentioned.
Did I mention OSHA? I gather you don't like the particular policy, but that wasn't my point and I didn't know what context GP was concerned about. Other people were talking about Europe.
Also, for the OSHA rules, they allow for a testing.
The goal posts will move wherever it's convenient for antivax crowd.