Public transportation is quite good in Europe compared to say, the USA, where car companies purchased intranational train tracks, dismantled them for highways
National population density is irrelevant. US population is just as urban as Europe. The lower USA average mostly reflects the southwest deserts and Alaska where very little rural population exists.
The low density of car-oriented US suburbs was mandated by socialist central land use planning from Washington and the motorcar industry that wanted to require Americans to each own a car. Standards were written centrally and local governments were required to make them law with grants, national bank regulations that required them for lending, and professional standards organizations that made civil engineers agree to them for licensure.
The more market driven land use in European cities promotes walking and transit more than personal motoring.
Cities old enough they were designed for foot-traffic, not car-traffic; modern-ish train systems and other public transit; the high price of fuel... My guess is less need.
It's complicated though. In the UK, for me, it's cheaper to buy and run a car than it is to use public transport.
We used to use hire cars for special trips and use public transport for other things (for a time having no vehicle by choice); then we got a scooter (as a couple) to help with going out and doing shopping trips and such (definitely cheaper than getting taxis).
Then work necessitated having a van, once you have a vehicle then it's only ever cheaper [where I am] to use public transport for long trips for an individual - once a couple or more travel together it's cheaper in a car (including a proportion allowed for road tax, ongoing license costs, depreciation, repairs and petrol [using Gov mileage allowances; not including learning to drive!]).
Problem is, as with many things when you're poorer, the upfront costs for a car mean that those less well off can be barred from ownership and so barred from the per-mile savings and convenience.
Having a car for our family now means I can't afford to take the bus and watching near empty buses go past as you walk home in the dark, cold and wet, isn't much fun ...
Scrap values being high has pushed the price of the lowest costs second-hand cars up a bit. Not so long ago I had to pay to have a still usable car scrapped to avoid paying the license fee. Bangers then were essentially free.
I can appreciate what you're saying, as the truth is that the cost of public transport varies wildly. I remember being surprised at how much better (cheaper, more frequent, higher quality buses) the bus service in Cardiff was compared to my home city (Bath). It's a bit of a lottery, not much you can do as (in my experience) it tends to be a single company that dominates the bus transport in an area.
shows the US at 809 cars per 1000, vs Italy at 682, Germany 588, and so on. Which I would interpret as "Europe has slightly fewer cars per person", not "Europe has NO NEED for cars". It's hard with a straight face for anyone who's visited Paris or Rome to observe there's not serious traffic. (And, in fact, woe to any pedestrians who get in their way.)
In most European cities you really do not need a car. That does not stop a lot of people from owning cars anyway out of convenience, and because they can afford it.
The numbers do not show a full picture. A lot of people in Europe own a car but use it only occasionally -- going on holiday, weekend trip etc., and still use a public transport - which is well developed in most (even smaller) cities - for everyday commuting.
