A lot depends on where you live. If you are in the suburbs with no access to mass transit, makes it very hard.
Same for if both husband and wife work. And kids (age and number).
And you need to change the title to 1 vehicle family to be completely accurate.
I am a 3 car/3 driver household, but have 4 vehicles (wife's SUV, daughters car, my truck, and my motorcycle) right now.
Soon to be a 4 driver household (my son turns 16 this year).
I could not get by as a 1 vehicle family.
I could get by without my truck. I have put 1,900 miles on it in the past year.
I only drive it to work when it is raining in the morning, and use it for errands that require me to carry more than I can fit on the bike.
If I did not have it, my wife could bring me to work on rainy days, and her or my daughter could pick me up.
So I could get by as a 2 vehicle family, I would just have to get wife or daughter to drive me to and from work (which is not bad, I am only 3 miles from work, and no, I am not riding a bicycle, it is too hot and only access requires riding on a road with a 50mph speed limit and no shoulder/bike lane).
But all my vehicles are paid for, insurance is not too bad, and it is just to convenient to not have them.
When my son starts driving, I have been debating giving my truck to my daughter (she has begged me for it since she started driving) and giving the car to my son, so we would be a 4 vehicle household with 4 drivers.
I do not look forward to the insurance of a 16 year old male, but on a 10 year old vehicle, it should be tolerable.