COTS stencils on coaches

Why do ARA coaches have giant black patch COTS stencils like a freight car, instead of stenciling on the air tanks, as is customary for passenger cars?

-otto-

I am not sure, but I have pictures over the past 7 years of five different numbering schemes, using different style and placement and color of the numbers. So, in a couple of years they might just be painted orange again.

So I take it there is no real reason for the giant COTS stencil? I thought they were only required for freight and MOW cars...