Dude, you were still in soiled diapers when this was added  

... beyond regional relief pilots!  It is a universal definition in the CBA now, used for lots of things past relief pilot per diem!

But, the safety issue was that pilots were being assigned and required to commute there on their own time, not on the duty clock.   It is still happening because the union allowed the verbiage to get in there to soil the water!

Has nothing to do with compensation!  Does have everything to do with duty time limitations because you've placed the ground transportation to an assignment on the shoulders of the pilot!  The union failed it's members here!

Relief pilots base is their home!   Home based!   CBA allows company to pick a location anywhere... so it isn't a relief's pilot choice how far he lives from his assigned base, from where the 50 mile radius starts.   So, pilot could essentially be burdened driving even further than 50 miles to get to his company assignment.   And, you are failing him for dismissing that commute as "rest" (not counted towards his duty time).

Their rules are fair, provided they count the commute as duty time!   Not concerned about the pay, but the SAFETY!