TV shows are sometimes criticized for lack of realism due to most of the cast being too good looking. What is a show that has mostly normal looking people?

Most British shows, so Peep Show, Fleabag, etc. There's even Episodes, which makes fun of this all in a very meta story about a British show being adapted to American audiences and requiring only hot people for the new version.

TV shows in the US are criticized for that.

You can do a fun experiment to notice this plainly. Watch the first season of Broadchurch (brilliant British series). Every person is a believable, next-door looking person. Even the proverbial beautiful woman of the town is played by Jodie Whittaker, who is beautiful but not stereotypically so. The main character is David Tennant, who is attractive but quirky looking, and his partner is Olivia Colman, talented and normal looking. She's perfect to play a cop who aspires to advance in her career but hasn't been able to. And her character is magistrally played.

Now watch the only season of the USian remake, Gracepoint.

Tennant is the only actor returning in that version. His partner is Anna Gunn, for crying out loud. She's stereotypically gorgeous, she looks more like a former model that like a career cop. The "proverbial beautiful woman of the town" looks like a porcelain doll. (And her husband is from a token minority, another posturing you won't see so clumsily done in a British series. They are more naturally varied in casting.) After seeing Broadchurch, all the cast of Gracepoint look like molded plastic.

[off topic]

I hate when they do a biopic and cast an actor who is much better looking than the actual person.

Tonya Harding was plain at best and certainly nowhere near as gorgeous as Margot Robbie

Kevin Can F*** Himself has a bunch of actors that I’d never seen before and are very non-Hollywood pretty.

The Office. Has an incredibly average looking cast

Resident Alien