While I appreciate Lipsitz's investigation of this area and his comparison of similar themes across several shows dealing with people with different family backgrounds and how they relate to the hegemonic structures in the world, I feel he does adequately address the bigger issue that depictions of working-class people in prime-time sit-coms, particularly those in unions, falls off dramatically by the end of the 1950s. This would seem to help his point that the rise of the commercial structure of the television industry, and the push toward making viewers into consumers might have had a role in this change. Labor union membership was near its apex in percentage of total workers in the early 1950s and would decline over the following two decades. At the same time, there seems to be a similarity in many of the working-class characters on the shows he focuses on where some of the characters are in union jobs, or jobs that could be unionized.
While private-sector union membership was certainly not the most definitive element of these shows, it certainly spoke to a certain class of viewer, even if they weren't members of a union themselves. Ralph Kramden drives a bus as is likely in a union (though it's hard to know if it was a public or private bus system); Chester Riley works in an airplane factory and is likely in a union; Al Murray, Jeannie's friend in Hey, Jeannie! is a cabbie in New York and is likely in a union. Even those characters who do no work union jobs would have encountered friends and family who did (like the Goldbergs in The Bronx). It could simply be a correlation without causation, but as private-sector union membership begins to shrink, there are fewer and fewer union characters in sitcoms, regardless of their ethnicity or race. (Note: The rise in public sector membership in 1961 was the result of protections Kennedy extended to federal employees to allow them to collectively bargain.)
There have certainly been union characters in the years since, including Archie Bunker (foreman laborer on a loading dock) and Roseanne Conner (in the early seasons she works in a toy manufacturing plant), however the default class of character for many shows seems to be non-union, non-working-class. The handful of shows about African-American characters (Good Times, The Jeffersons, The Cosby Show), generally put labor rights behind other family comedy and melodrama (not that there's anything wrong with that). Then you get shows like Friends (do they even work?), Seinfeld (they sorta work or their work is rather silly and they live really nicely), Two and a Half Men (Charlie's job is purposefully light), and The Big Bang Theory (scientists whose intellectual work lets them get off around 5pm every day to eat Chinese food). It seems like aside from losing the rich diversity of early TV sitcoms (which might be starting to come back) we also lost a diversity of class and labor opinions.