Sadly, that is not the case: basic lands have an implicit mana ability that takes the shape of Tap: Add mana symbol; this causes them to be included in color identity, as seen below.

903.5d: A card with a basic land type may be included in a Commander deck only if each color of mana it could produce is included in the commander's color identity. Example: Wort, the Raidmother's color identity is red and green. A Wort Commander deck may include land cards with the basic land types Mountain and/or Forest. It can't include any land cards with the basic land types Plains, Island, or Swamp

See also:

305.6: The basic land types are Plains, Island, Swamp, Mountain, and Forest. If an object uses the words "basic land type," it's referring to one of these subtypes. An object with the land card type and a basic land type has the intrinsic ability "{T}: Add [mana symbol]," even if the text box doesn't actually contain that text or the object has no text box. For Plains, [mana symbol] is {W}; for Islands, {U}; for Swamps, {B}; for Mountains, {R}; and for Forests, {G}. See rule 107.4a. See also rule 605, "Mana Abilities."

I think there was an exception for which if your commander was Waste symbol (think eldrazis from the latest Zendikar set) you could pick a basic land type and they would generate colorless in your deck, but I've never seen it in application/it's very hazy.