I can't disagree with Annelia Alex's observations...but I don't think it's limited to the 1990s, or to sitcoms. I remember watching The Waltons with my parents back in the '70s. Dad would often make this statement at the end of the episodes: "Dirt poor, but they had that big house and owned the whole mountain!"
Personally, I've found it surprising that some characters have such nice homes, given the circumstances they're supposedly in....
My mother's gripe was against a popular nighttime soap, Dynasty. When Joan Collins joined the cast as Blake Carrington's scheming ex-wife, Alexis, and moved into a house on the Carrington estate, she made a habit of entering the main house without invitation and doing whatever she pleased. Mom always found this annoying. Perhaps because, like Blake's then-wife, Krystle, Mom was a second wife. "I'd send her ass flying back out if she barged into my house!" Mom declared on more than one occasion.
Soaps are guiltier of stretching reality than most shows. The Bold and the Beautiful is an example. The show's current resident scheming shrew, Quinn Fuller, has gone to some pretty ridiculous lengths to make sure her son Wyatt wins the hand of clueless blonde heiress Hope Logan, even coming close to killing Wyatt's half brother/romantic rival, Liam Spencer...and Liam's the only one who sees through her lies.
I guess Mommy doesn't think her son is wonderful enough to win the girl on his own charms.
But getting back to sitcoms...my favorite, The Big Bang Theory, is chock full of "that would never happen in real life" moments. Most of them involve resident genius/pain in the butt Sheldon Cooper. Sheldon may be a genius in physics, but he's hopeless in the everyday world. Sarcasm eludes him. He believes the world revolves around him and drives everyone around him nuts--yet they allow him to rule their lives, always choosing where they eat, what movie they see, etc. He has a schedule for everything--including bowel movements! His roommate, Leonard, also a physicist, had to sign a detailed (and absurd) roommate agreement to move into the apartment. He's not only a roommate, he's Sheldon's personal chauffeur.
Sheldon and Leonard have been roommates for seven years. In the real world, Leonard would have either moved out or murdered Sheldon within the first month!
Last week, in the show's season finale, Sheldon was upset at the news that Leonard is going to marry Penny, the aspiring actress/waitress who lives across the hall."You're putting [her] happiness above mine?" Sheldon demanded incredulously.
"Well...yes," Leonard admitted.
Sheldon couldn't believe it. Seriously, he was baffled that Leonard wouldn't put him first.
I'm not quite sure I believe it, either. Beyond her looks, Penny's not much of a prize. She drinks too much and has been a bit of a tramp. On occasion, she's made comments that would indicate she thinks she's too good for Leonard. But the good-natured, neurotic physicist with painfully low esteem happily overlooks that...okay, I guess some guys would put up with anything to get the girl....