Cash is just a less restrictive format. No definite start and end time, stakes can change, game can change, people come and go as they please.
Compare to tournaments, where you could conceivably have Spirit Airlines (RIP) level fights erupting over seat choice in competitive tourneys for big money. Then someone has to step in to make decisions, and it's better to just save the headache and do assigned seating so everyone can stay civil and on schedule.
Never seen it become an issue in cash. You just sit down and play. If you jump seats a lot, you get penalized with extra blinds. You may also get shut down by the house/host if it's disruptive or you're clearly trying to harass someone.
Sure, I get that. In a casino where everyone is on a different time table. But at most home games I play in, including mine, the potential to lose "BIG MONEY" is in the cash game NOT the $100 or whatever amount tournament. So I would argue it's more important where you're sitting at home cash game vs a home tournament because you have a lot more to lose.
Also my home game is weekly with roughly the same crew. Each week is it's own 6 hour episode. People don't show up late or leave early without good reason. There's no hit 'n run like in a casino because if there is guess what? You're not invited back!
Semi annually I will have a bigger game that starts earlier & like @Gavin (https://www.pokerchipforum.com/members/3001/) I will do a re-draw midway through if someone requests it.
Ultimately you're right though when you say it's not a big deal. And neither is having seats randomized : )