How do I properly lock my bike in a city where bike thefts are common?

Or just boltcutter the locks off all the other bikes in the rack. Thieves will think twice about stealing your bike when there are a half dozen better choices.

I live in a family of 6, and we were able to live car free for a year when we lived in germany. My dad used to live and work 300 kilometers away, and he would visit us every few weeks, coming by high speed train. My mother did all the buying groceries by bike. And we didnt live in any big city. It was a town of less than 10.000 people. It is possible for families to live car free. We did roadtrips by bike, visited nearby cities, went to beaches by train. We did have the car of a relative available, but we used it some 5 or 6 times in the whole year.

I dont care if you have a family, you can live car free, if in the right place. And we aren’t super rich or anything, we lived with our relatives, and my dad lived in a friend’s house, who gave him a very big discount.

And we also didn’t have any 3 bikes each, our bikes were mostly oldies borrowed from old family friends who didn’t need them.

And if you do the math, 100 dolars a month, is pretty cheap for a car, if you consider gas and wear, so it is cheaper to buy a pretty nice bike every 3 months than to own a car.

That's a very America specific thing and not applicable to most pieces.

Which is why I take it to mean "replace applicable travel events with bike rides". I can't go carless in a suburb, but I can cover many daily needs with a bicycle. This is from someone that regularly commutes by 80mpg motorcycle and uses it for many grocery/light shopping needs, so it's not a fear of cargo/passenger capacity.

Similarly, this is what shoots the rail dream down. Yes, it's nice to dream about the freedom of a train ride taking you to a fun destination. But then what? You arrive at the city and then... Stay in the city? Hope it's a city at all? If it's a decent-sized city with an airport, a car rental will probably work out fine enough. But then how did you get to your train station? Well, probably by car too. The regrettable situation of the US is that it's not just a cute little country jam-packed over millenia. It's as vast as the entire European continent with the population heavily concentrated on the coasts. If visiting cities are your thing, it's easier to work out. But no, we're not going to completely revamp the rail system to be "like germany, Spain, France, or England" because we already have that. It's just in a straight line from DC to Boston. The area triangle made by London/Paris/Berlin is very similar to Boston/DC/Detroit. In the same way Americans generalize "Europe" to mean Spain, France, Germany, Poland, Italy, and the UK, ignoring all the east Europeans, we forget how empty it is between the Mississippi River and the west coast states - roughly half the continental 48 states house just 26% of the continental population. That's including Texas in the middle with 9% in itself. The carless infrastructure drops quickly because population density drops quickly. The cities are largely isolated by seas of suburbs or emptiness.

Whatever, tangential rant. I love rail, I work in rail, I rode the acela for fun. But we can't right suburbs without displacing half the population. There is a strong westward density drop-off after the Mississippi River, a small one after the Missouri, and a sheer cliff after the line dropped from Winnipeg to Dallas until you get within 50 miles of the Pacific. That's a 1300x1300 mile square of emptiness.

limited to only single or childless adults

I think this is too narrow of an assessment. More common in America than single adults living alone are two adults living together, with each having their own car. So while you're right that the present American land-use reality isn't exactly conducive to having a plurality going car-less, it's entirely probably for a couple to save substantial money by switching one car for a bike and keep just one car for the household. That's something that can apply in huge swaths of the country, although it's exceptionally apt for cities.

So it basically is not applicable to millions of Americans, with our massively large square mileage of country that we occupy.

It's funny to me when people use the US's land size as a reason for needing a car...as if they live in Miami, need to commute to New York for work every day, and have to pick up the kids off from daycare in Anchorage after work.

It's not the geography that necessitates cars. It's poor city planning.

And now it's weirdos protesting things like 15-minute cities, as if being able to walk to a grocery store, a department store, a doctor's office, schools, and a park within 15 minutes from home is a bad thing.

Even a scooter or motorcycle is better than a car (though not necessarily safer).