and as far as I know the US did do exact the opposite en mass
GMO by itself isn't bad, but a lot of GMO is made in a way which is harmful to the soil on the long term (and sometimes even short term)
Similar much higher limits for the amount of fertilizers used allow you to use approaches to growing crops which short and mid term have more yield but also drain the soil in a non-substainable way leading to a death spiral of needing increasingly more and more fertilizers, insecticides and at some point GMO modified crops.
While most EU countries had for a long time (but not necessary still have) laws which require a more sustainable ground usage and having a larger movement of people buying food which even more stricter constraints wrt. fertilizers and pesticides.
While this may be causal, agriculture is incredibly complex, and I would hesitate to come to any conclusions about causality from this bit of data alone.