Let’s assume you are over 1999kg and filing a Eurocontrol IFR flight plan.
What stops you designating almost any flight as a “training flight”?
Obviously this is a big attraction of UK Class G. You just depart “VFR” and arrive “VFR” and you don’t get a bill. But the same must work everywhere else too, in any airspace where you can get a VFR transit. Obviously nobody will be doing this in actual IMC 
but if they did nobody is going to find out.
The Q is how does Eurocontrol ever find out – because I am told that sometimes they do invoice you.
A CFII might be cheaper per hour than Eurocontrol route charges so this is a good suggestion 
The exemption is not granted in Germany which is probably why I’ve never heard of it.
Interesting to see that Italy imposes route charges for VFR above 2 tonnes.
Bingo. Since you’ve mentioned what people have been secretly doing on a public forum, now they will actively start cracking down on it.
