The Netherlands has done a great job investing in infrastructure, but it's not really a typical place. Even when you include all the land set aside for farming and nature, the population density is very high. The region here is about the same physical size and has ~300,000 people. Dedicated infrastructure is often helpful, but there's not the resources or justification to build it everywhere.
As density goes up, the need for specific infrastructure goes up, but you don't have to get as intense about it as the Netherlands does to create an environment that's safe and pleasant for cyclists and pedestrians.
Montréal, for example, is about as dense as any other large North American city (which is to say, not very), but still does a great job without, from what I can tell, any serious expenditure of resources on physical infrastructure. There are a few physically separated bike lanes, but mostly the city just focuses on calming down the traffic: More one-way streets, left turns permitted at fewer intersections, and a ban on turning right at a red light go a long way toward making the city's streets more pleasant for everyone.
I even find it's more pleasant to drive there than it is in my city.
