In the 1970s Amsterdam looked like pretty much any American city - it may have taken a few decades but changing the transportation focus of a city is an extremely accomplishable goal.
Amsterdam never looked like American cities, central Amsterdam doesn't even have roads where cars would fit.
Since 150 years an extensive tram network existed, with horse carriages like in many other European cities before it was electrified.
Every part of the city is walkable and always has been.
Few cities in the US are comparable, maybe New York but it's not really desirable to live there for a lot of reasons - being full of cars in a place where none should be being one of them.
The european cities have a problem with roads not broad enough for cars. In a city that have broad roads that fits more than four car lanes, you can easily split one lane off physically from the car road and make it into a two-way bike lane.
When the population are used to this and the car trafic goes down, the bike lane will be too crowded to be a two-way. Then you do the same on the other side of the street and make them both one-way roads with car lanes in the middle.
In our town they are rebuilding the bus stops on streets so if two busses stop, they will block the whole road for car traffic. The bikes can pass on the separate bike lanes though. This by design so people will choose bike instead of car. Not quite thought through though since this will also block blue-light traffic...
Population density is too low because cities were designed with cars in mind. 50% of the population lives in the suburbs where it is just too far to walk anywhere and even if you look at more densely populated places everything is still quite far away. Nobody wants to walk 20 minutes just to get from their house to the bus stop and even if they did, you can't make low intervals for bus routes work - much less outside of peak hours. But to replace cars by public transportation you need it to be reachable, high interval and ideally available around the clock.
Labor cost and cost of living is so high that it prohibits the existence of small neighborhood stores. I live in South America and have lived in many different places here, you can buy everything within walking distance wherever you are. In my neighborhood probably 5% of the houses have a small shop. Twice per week the streets turn into a market in different parts of the city. Even in the big cities you have small convenience stores operated by families in every corner. Public transportation is probably the best in the world, you can go anywhere without a car for very low prices - even for our income levels.
Europe is somewhat in the middle between these two. Public transportation doesn't get you everywhere and its expensive. Most small stores which existed 30 years ago are dead because of supermarkets and online stores. You still won't see extreme examples of a car-centered culture like public high schools with 5000 students and you can usually get to a smaller supermarket within 15 minutes. But having higher labor cost lead to more centralization.
Also keep in mind that the first thing people buy once they have money is a car, even if public transportation works. You see this in places like China. We won't get rid of cars anytime soon. The best outcome we can hope for within the next 50 years is driverless ridesharing.
Since 150 years an extensive tram network existed, with horse carriages like in many other European cities before it was electrified.
Every part of the city is walkable and always has been.
Few cities in the US are comparable, maybe New York but it's not really desirable to live there for a lot of reasons - being full of cars in a place where none should be being one of them.