When she allegedly/would have worked there, franchise employees were still considered employees of the McDonald's corporation. That changed later, but she would have worked there circa 1979/80 (according to her age, and her narrative)Iirc she never mentioned it in her memoirs or any other place and it only appeared in her recent stories of her childhood in an attempt to make herself more relatable to middle class.
Oh and she lies about everything else.
Either way, the IRS could clear it up in less than a minute.