The cost savings must be good enough that the company is willing to put up with more negative PR from their relationship with Menzies:

Workers on leave after Alaska Airlines jet bump | KING5.com | Seattle Area Local News

The local media loves this stuff.

BTW, I think Menzies will determine that wing-walkers are useless and eliminate them on the push-back. If they're not actually looking at the wingtips and obstacles in the way, then why should they pay extra people to do this job? They'll go ahead and let 2/3 of their workforce go.