It is a disgrace that they don't share traffic data.
Hmmm, I don't see why they should have to share data. After all they're only sharing data of who that have on their system, what about the other traffic not on either system. Why don't Air Services/Airways share their data since they will see pretty well all transponder equipped traffic especially with all the new MLAT gear?
We all have to remember that not all aircraft will be shown on any traffic system (some aircraft non Xponder equipped or turned off) and we all need to be aware of this and keep a look out as much as possible. I fear there's too much gadget gazing and not enough old fashioned lookout going on in some cockpits.