It is not accurate to say there was no collaboration with the Germans/Nazis in Poland during WWII. While Poland was known to have had a particularly strong organized resistance movement (the Polish Home Army) which worked underground to undermine the German occupiers, there were also Poles who did work with the Germans. Perhaps the best example of this is the Polish Blue Police (also known as 'uniformed police'). They operated in the section of Poland called the General Government, subordinated to the German Odnungspolizei (Order Police). Alongside the German Ordnungspoliezei they conducted anti-Jewish measures, including: acting as escorts when Jews were forcibly relocated, tracking down Jews in hiding after waves of mass killings took place, guarding the gates of Ghettos, and executing some Jews who had been sentenced to death by the Germans. (For more on the Blue Police, see Jan Grabowski's chapter 'Poland: The Blue Police" in How Was It Possible?: A Holocaust Reader by Peter Hayes).

While the Blue Police offer an institutional, organized example of Poles who worked for the Germans to assist them in carrying out the Holocaust (which absolutely fits the definition of 'collaboration'), individual Poles also aided the occupying Germans by denouncing Jews in hiding. In some instances, this may have been done out of fear for their own lives, but in others, the desire to seize the property of these Jews, or to avoid returning goods that had already been seized, was also a motivating factor. (See Jan Gross's Fear.) In some cases, people agreed to harbour Jews in exchange for some form of payment. Later, when payment stopped because the person in hiding had run out of money, that same person turned the hidden Jew over to the German authorities (or Blue Police). In other words, individuals could serve as rescuers for some time, and then later decide it was in their interest to work with the Germans (collaborate). Collaboration was often a complicated, messy process. The sweeping statement that there was no Polish collaboration is patently false, since Poles did collaborate.

The Polish government did not collaborate with the Germans, but there was no Polish government left in Poland to do so, which makes it hard to use this as evidence in Poland's favour. Poland was carved up in mid-September 1939, with part taken by the USSR and absorbed into Belarus and Ukraine. The remaining part of the country was subdivided, with part annexed to Germany and the other section renamed the General Government. Poland as a coherent entity ceased to exist, so it is hardly a surprise there was no polish state collaboration.

I will note that Nazi ideology did have a low opinion of Poles based on racial theories, which played a role in determining how Poland was treated, as opposed to, say, occupied France. This helps to explain why the Germans showed no interest in working with a Polish state, and instead worked to dismantle it. Still, for pragmatic reasons the German occupying forces were willing to work with some Poles, since there were never enough Germans in any group of occupational forces that they did not need some help from locals.