Having said this I do notice that while my attire is the norm in the US it's out of the norm in Europe and elsewhere.
And vice-versa, this "greasing" of yours may be the norm in the US, but certainly not in central and northern Europe! If at all, then the owner or passengers will tip the handling agent, but we pilots? From our salary? Sometimes, we will offer the leftovers of our catering or a bottle of beer to a refueller, but that's it. And we are not used to getting tips ourselves. Not from corporate passagers anyway.
But here (central and northern Europe again), too, it is the crew ID rather than the uniform that opens doors.