No matter if Dutch or Flemish - Belgium and Holland both are relatively small countries, so the probability of finding many long-haired girls from there on a forum like this one should naturally be quite small from a statistical point of view.
Besides, neither of these countries is known to me as a culture in which very long hair is celebrated and encouraged traditionally as a value and a goal in itself, as it is for example in Russia, Colombia, India, and generally in Asian countries, nor is very long hair very common in Belgium or Holland (my observation from travels).
While in the US the prevailing attitude makes women wear shorter, maintenance-intensive hairstyles, the country´s 340 million people still produce an impressive number of exceptions - women who don´t care about the official trend and grow their hair out to extreme lengths.
In a magazine dedicated to Texas, I once found the photo of a woman dancing with ankle-length hair, and the caption said: "They say everything is bigger in Texas, but sometimes it´s longer."