On the occasions you are moving something larger than can fit in the bike you can take a cab/rent a car or truck. If you are regularly transporting things larger than the cargo bike then perhaps you need a car but I guarantee you 99% of people are not moving 300L of sand every weekend.
Also adults and people older than 10 can ride their own bikes.
Wear a cape and some rain pants: https://cleverhood.com/
The Netherlands is also notoriously rainy and windy.
The point is you can replace 90% of your trips with a bike, not that you can never have motorized transport. 90% of car trips in America definitely do not need to be in a single occupancy vehicle/only need to be because we've put everything so damn far away from everything else to accommodate cars. The latter part of the second statement does not apply if you live in a pre mid 50s city
Partly it's because I live in a city with rubbish traffic on weekends, so a weekend like you describe would be full of crawling traffic and hunting for parking spots.
Having a weekend like you describe - which I remember more from other cities - is something that you can do because of the ways cities are designed (big box stores!). Not wanting to be a moral scold, but a lot of cycling advocates would just say "spend your weekends differently". That's not what I'm saying - and elsewhere I complain that a lot of cycling advocates seem to assume everywhere is already set up like Amsterdam in terms of population density and flatness. However, spending every weekend piling into a vehicle to schlep around big box stores is a choice, just like living in some dense area and cycling everywhere in a cutesy whole-family cargo bike.
You use the word 'need' a lot, even for stuff like "breakfast at a cafe" ('mom: we have breakfast food at home', as the meme goes). A lot of this stuff is choices.
There are different types of bicycles, and different types of carriers you can attach. For example there's a cargo bike [0]. In a bicycle focused city you'd perhaps be able to borrow/rent a bicycle for specific uses.
I guess the rain can be a bit of a nuisance, but from my understanding it becomes a non-issue once you've got the proper gear for it. Plus if you were bicycling to work for example, you could have a change of clothes there.
By the way mrmoneymoustache.com has some blog posts about his primarily-bicycle lifestyle in Boulder, Colorado if that's relevant to you.
[0] http://greenlivingideas.com/wp-content/uploads/2012/05/cargo...
Yet somehow those millions of families get by just fine without cars. I'm not sure why you think it is complete impossible.
That said, if you're having to buy 300L of bagged sand _every week_ then no, it doesn't seem like a particularly fun time and frankly I'd stick with a car.
Advocates of cycling, I would be genuinely interested in how you would logistically achieve a typical weekend day in my life, which might consist of:
- Transporting myself, my wife, my daughter, my dog, and (say) 3 large bags full of the stuff that they require from my house at the rural/suburban boundary to the part of town where the hardware stores are - about 25km away, with about 600m elevation change.
- At those hardware and big box stores, I'll need to buy (say) 300L of sand (bagged) for the sandpit, a new powertool, a bag full of clothes, and a new bed for the dog.
- We then need to have some breakfast at a cafe, and transport the whole lot home.
- We have to do all of this in the rain or in the very high winds that my city is famous for.
- Total time to achieve all of this has to fit between my daughter's naps, so we have about two and a half hours all up.
Some version of this is my life almost every weekend.
Now, I would genuinely like to hear how I could achieve anything approaching this using a bicycle. I'm not being facetious - I don't know how it would be possible at all - but cycling advocates seem determined to assume that I somehow can, so I'd love to know how.