Big dairy's collusion with the US government is a much deeper issue than anyone suspects.
Here's a good read on it, I wish everyone knew about this:
https://www.pcrm.org/news/news-releases/doctors-denounce-government-partnership-pizza-hut-push-cheese
tl;dr The US government is partnering with food manufacturers (and Pizza Hut) to increase the amount of cheese in products in order to prop up the dairy industry.
When it comes down to "can oat milk be called milk?" I think the outcome is a foregone conclusion.
FWIW - I consider myself "lactose ambivalent". I'm not intolerant. :) It just doesn't occur to me to buy dairy most of the time.
I do enjoy Oat Milk, I wish it didn't have as much sugar in it as it does. :( It really doesn't like me though!