Since Tatooine is in Hutt space, and in The Phantom Menace we see basically everyone on the street on Tatooine defaulting to Huttese as their primary language, wouldn't the Lars family (and thus Luke Skywalker, having been raised by Owen and Beru Lars) speak Huttese as their first language as opposed to the Galactic Basic we see them speaking in A New Hope?
They've been there for at least two generations, since we know Lars' father Cliegg was also a moisture farmer there, as was his mother Aika - plenty of time to adopt Huttese as their first language, even if they were immigrants prior to that.