@Klauss,
Aviation was already prepared in 2010, the blanket rule grounding was decided by clueless officials and politicians who wished to be absolved of any blame whatsoever. Aviation could have continued happily with some dynamic airspace restrictions, as they do with impunity in many areas of the world where volcanic eruptions are an everyday event. The reaction was not all that dissimilar to how the Covid situation is being handled...
The fundamental problem in all these cases is that there is a knee-jerk reaction to demonstrate that something is being done to protect the public, and reversing such decisions is very difficult since it usually involves an admission that it was unnecessary in the first place, combined with the courage to say that nothing further will happen (and the risk of being blamed if something does happen).