For the record, the factories didn't have much to do with cable routing. Bikes arrived at bike shops disassembled and in boxes. The LBS assembled them and made any determination about cable routing.

More often than you would think, catalog shots had poorly assembled bikes in the product shots. Presumably this was because they dragged bike boxes to a photo studio, without getting them professionally assembled.

It's true sometimes Peugeot shops would route cables under, especially older ones with under TT routing. They were an exception. May have been more sloppiness than preference. Schwinn may have had guidelines, but I never worked in a Schwinn shop so I don't know.