People go shopping, they don't want to carry on $200 worth of groceries onto public transportation.
Finally people have kids. Kids require a plethora of specialized items including car seats. I dont want to put my kid in a car seat a prior kid just urinated in. Kid's are also messy and require snacks and water bottles.
People who can afford it are going to take cars. I hope The Boring Company is a rousing success.
I am not arguing against the need for mass transport but I see no reason we cant have both.
Your point about rural scenarios is pointless because this video and idea are clearly aimed at the urban transport problem which needs to be solved due to the fact that, around the world, people are increasingly moving to cities rather than the to rural areas.
When it comes to shopping, I don't know about you but I often find myself looking at other peoples trolleys and asking myself "Why would anyone buy 10 2L bottles of coke? Do you really need all those doritos? My word random stranger, do you subsist entirely on junk food?". There are times that one does come away with a large load of shopping but my wife and I have found that when you start planning your meals for the week and optimising what you buy to fit that plan you tend to come away with a lot less shopping than if you just go in an randomly buy stuff. Would would have guessed?
Your point about children is good but ignores the fact that there are huge numbers of people throughout the world with children who somehow manage to make life work despite not owning a 7-seater SUV...
I think it's better to say that people who can afford it might want to use a car now and then but they'd probably also love to have access to viable public transport for all those scenarios where getting into a car is more trouble than its worth.