There may have been technical limitations. I'd recommend Orlando Figges' "Natasha's Dance" for Soviet culture and his "The Whisperers" for how people behaved under the Stalin regime. There's a full discussion in there (somewhere - it's been a couple of decades since I read them). For 'kitchen speech', I'd start with "The Whisperers". The TL;DR of it as I remember had to do with where in the house / apartment the kitchen was located, hard tile / masonry / plaster surfaces and the state of microphone tech (pretty sure they were pretty much all carbon mics). And then they'd need someone actually listening. The Germans in WWII came up with wire recorders (sort of an early kind of tape recorder) but those weren't in general supply so it wasn't possible to record everything, then on playback skip forward through silence. I'm not saying they couldn't record audio, but that those were reserved for people under close scrutiny, not Uncle Vanya and his family.