Some areas such as Amsterdam though are just naturally more ammenable to walking, cycling, and transit. Cycling in 90+ (F) temperatures with high humidity (very common in the summer in the US midwest or south), or even just walking very far or waiting very long for a bus is pretty miserable. I'd arrive at my destination literally dripping with sweat and really unpresentable.
Somehow Singapore being 1 degree from the Equator manages to have a bus network, a metro and practically caps the amount of cars on the roads.
Also, you seems to underestimate how bad the weather in Amsterdam is. Cycling on a bridge through rain against the wind at 5 degrees (C) isn't very fun either.
When I lived in a more hotter climate, 30ish (C) was a-okay for some people to cycle to work and then get a shower at work. It's all about infrastructure really --- be it showers, speed limits or bike paths.
I sure that Amsterdam has plenty of Dutch hills.
My wife used to live in Bristol, which has plenty of hills, and she was biking everywhere. That's why she has a nice butt.
If one needs excuses to justify having a car and being stuck in traffic, hills ain't a valid one. 30km/h is great, makes for less noise, less air pollution, and now we see, it makes it for 0 traffic deaths. Much better to have the option to reach a grocery store on foot, by bike, by public transport and car than have no options but a car. That makes for less cars on the road, and, funnily enough, 30km/h on a non-busy road will often get you faster to where you want to go than 50 on a busy one.
Again, that's why we Europeans are both happier and fitter than our American counterparts.
I'm not sure how common the term is (I heard it in a YT video), but a "Dutch hill" is wind, because the Netherlands is very windy, and anyone who's ridden a bike in heavy wind knows that it can be just as much an obstacle as a moderate hill.