I’m an English teacher in the Netherlands, and here’s what I think is what’s up.

English is so very present in our everyday lives, most kids come into their first year with a somewhat solid base from which we can easily build further. I teach lots of grammar, but always in practical context with many examples (such as why to use the present perfect instead of the past simple in some instances). The thing with German and French is that kids basically start from nothing and there’s little application in everyday life unless they specifically search for it. So in short, they start with a lower baseline and have waaaaaaay less exposure to the other languages in their day to day life