Hi, kinda new to the forum and desperate to chime in here on this one...
I can't believe nobody has mentioned the British method of washing dishes by hand. Let me summarize: Fill a dirty sink or dishpan with soapy water in the morning. Drop dirty, unrinsed dishes into that water all morning (or all day sometimes), wash those dishes in the dirty, cold water they're sitting in, place the dishes, UNRINSED, into dishrack to dry (or towel dry with a dirty tea towel). This is a truly cringeworthy habit. And to all my British family members, I'm the weirdo who rinses the soap off the dishes!
Sometimes when at other people's houses, I can taste the soap in the cup/glass I'm drinking from. It's especially noticable when drinking beer. Best to skip the glass and drink straight from the bottle or can.
I believe this habit comes from WWII and just stuck. It would be like us never throwing anything away because that's what our grandparents did (because they grew up during the Depression). I have read that it's regional, but I'm not so sure. So far, I have never seen a British person anywhere rinse their dishes. They don't even rinse on the Fairy liquid advert I just saw the other day!