Where's the evidence this difference is specifically due to the population or "size" of the country rather than history, culture and any other factors? It's like you put two countries on a scatter plot and drew a line from them.
The Netherlands have been flooded multiple times over the centuries and this has contributed to the idea of helping the people in difficult situation. I don't recall exactly, but after the flood of 1825, a fond was started to collect money to help the ones who lost everything. And a large part of the population contributed money into it as everyone knew a relative or friend who lost some property, his home, or some family members. So geography and history have a part in the way the Dutch care against adversity.
Here is a list from English Wikipedia about the floods. The Dutch Wikipedia has much more info on the flood, as well as a museum in Leyden (from Rijkswaterstaat if I remember well). Not everyone can read the Dutch language.
https://en.m.wikipedia.org/wiki/List_of_floods_in_the_Nether...
