Cessnapete,
It appears your experience is similar to most people's.
What you did was illegal in both the Netherlands and Belgium (you haven't given enough info to see if illegal or not in Germany) but nodbody seems to give a damn.
It's illegal to go above 1200ft in the Netherlands without mode S, yet most people report that they are routinely invited to go higher with mode C. You are not even supposed to activate mode C in the Netherlands, but again most people are asked to (as indeed I was in the past too).
According to an AIC issued last year, you need modes S in Belgium, but very few Belgian pilot's whom I've spoken to know about the AIC, and even fewer have mode S.
Oh, and unless you have an installed ELT (PLB isn't good enough) you can't fly into or out of the Netherlands. Flying internally without is fine, but you need it while crossing the border!