During the Meiji period, the Japanese implemented major innovations that they sought from and found in Western countries.  France and the United States had significant influence in the modernization of the Japanese educational system.  I have read that Germany did as well, though not as prominently.  So why students latched onto a German word, I don't know.  For Japanese, Arbeit is arguably easier to pronounce than travail, but quite harder than job.  Then again, towards the end of Meiji, the poor bastards had to wear school outfits based on Prussian military uniforms, and Prussia was the rising big dog in Europe, so maybe German was the foreign language to use if a student wanted sound tough and cool.  (Pure speculation.)

Truth unfolds in time through a communal process.