In the 70's, there were two boys who captured America's collective hearts by appearing in commercials. Rodney Allen Rippy, for one, shilled for Jack in the Box restaurants, and parlayed that into a gig with the Harlem Globetrotters for their short-lived Saturday morning comedy show.
Mason Reese, on the other hand, attracted the attention of other sponsors, including Underwood deviled ham and Dunkin' Donuts, and was a frequent guest on The Mike Douglas Show. In 1975, he attracted the attention of Filmways, which shopped a sitcom pilot headlined by Reese. ABC bought said pilot, but it sat on the shelf for 2 years before it finally saw the light of day in 1977.
In Mason, Reese is a child prodigy attending a special school in New York, but otherwise is a handful for his parents and older sister. Reese, now 52, has his own YouTube channel, from whence we get the pilot.
I think you can see why ABC waited two years before this aired. There are some good moments early on, but confining most of the action to the home doesn't give this much room to maneuver.