Volcanic Ash - why not go around it?

So it may be that Spain probaby refused a reroute of all air traffic to it's airports & then have ppl take trains up to northern europe (if a train stops, it doesn't fall to the ground). But what confuse me is why the world leaders didn't do that for the funeral of the late Polish President and the traffic air crash. 2 funerals unattended. A shame.