What's the "special privilege?

Maybe you don't understand the purpose of Opus Dei.
Opus Dei exists to provide additional formation to ordinary lay people who want to pursue holiness and do apostolate in the ordinary world.  It has no geographical boundaries...because "ordinary people" are living everywhere!

It doesn't exist to run parishes, preach, prepare students for First Communion, teach in Catholic Schools, do mission work, like various respective religious orders do.   

Its priests aren't religious priests....they're secular priests...but everyone was first a member of Opus Dei.  They had a calling to live out their life with a certain spirit of holiness and apostolate.

It's sort of flip flopped compared to what you're perhaps used to.  The lay don't exist to serve various activities of the priests.

The priests exist to serve the lay, as they return for more help and direction and formation in order to better live out holiness in their ordinary work.