Movies and radio shows from the 1920s through the 1950’s/1960’s often portrayed African-American women as maids or domestic help. For example a popular radio personality in the 1940s was a maid called Beulah. ( Somebody bawl for Beulah) and was actually voiced by a skinny white guy ( google Marlin Hurt). But the accents and inflections were the same as the ads posted above.
Funny, the way the Happy Days ad is written is how most kids spell when they text today.