Just for example: When I visit my family over holidays, they live 10 miles from the nearest bus station, 35 miles from the nearest Amtrak station, and 100 miles from the nearest international airport, nearly two states away. There are no local taxis, busses, light rail, nothing. I'm not sure how public transportation would ever work for this kind of trip. This is the case for the vast majority of small towns in the USA.
Assuming your family have a car, wouldn't they meet you at the bus station/railway station/airport?
Mine almost always do, even though there are much better public transport options than you have. I don't generally have any use for a car while I'm visiting them, so there would be no point renting one.
(I can see this would be different if you are a family of five or similar.)
Public transportation works for that type of trip in some places. Not in the US though. If the dense cities can't even make it work where it is easy there is no point in trying those places that you point out where it is hard.
