A bit simplistic, and I've never seen a government agency say "deer can't see orange"
it, like many things is far far more complicated than that.
This is a bit old, but good info none the less.
https://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1279&context=icwdm_usdanwrc
It has been known for some time that deer can in fact see orange. That however does not mean they see it as we do.
the reason hunters are required to wear orange is in a broad and rough sense because it is one of the lesser noticed wavelengths for them, and one of the more noticed for us. At the end of the day It's hard to hunt successfully when you're dead after being shot by another hunter, because like deer- humans are idiots as well.