About two thirds of Jews in the Netherlands were deported East to their death, whereas much lower percentages of Jews were deported from other Western European countries. Why?
Here is a link to a paper about this very subject.
I can very quickly give you the two 'main reasons' as stated in this paper.
Terrain and Dutch Bureaucracy.
The terrain in the Netherlands and it's position in Europe were very unforgiving to any fugitives or resitance fighers. It shared a border in the East with Nazi Germany, in the South with occupied Belgium and in the North and West is the North Sea.
Hiding was difficult as well, as the Netherlands was very densely populated without many forests, hills or any mountains.
The Netherlands was also very keen on Bureaucracy. It had civil records of age, sex and unfortunately religion amongs other things. This made it easy to know for the Nazi's who were jews.