We colloquially call a lot of things I’ve cream that aren’t labeled ice cream, and aren’t legally ice cream.

The US has tediously long definitions for different foods, and ice cream needs specific proportions of milk products, as well as limits on other physical properties.

www.accessdata.fda.gov/scripts/…/cfrsearch.cfm?fr…

www.accessdata.fda.gov/scripts/…/cfrsearch.cfm?fr…

www.accessdata.fda.gov/scripts/…/CFRSearch.cfm?CF…

So while I might pick up some sherbet and say “I got ice cream”, and people would know what I meant, it would never be labeled ice cream.
I also like oat milk ice cream, but it’s actually labeled “frozen dessert” because it doesn’t contain dairy.

The company isn’t allowed to use a term that might mislead a unwitting or uninformed consumer, but the consumer is free to have a more relaxed definition, and stores can put things where you would expect.