Poor Drafting Practices
Joe, I think I know why that is the case with McMaster Carr (not a defense mind you, merely an explanation of how it happened).
I believe they are using Solidworks as thier cad model engine. solidworks's 2d drawings, when exported to Autocad have that very same issue. Solidworks scales the views instead of the titleblock. as long as you are inside solidworks this is seamless and causes no problems because it knows internally that the view is scaled. it only causes problems when you export.
long before the advent of 3D modelers, Penn Engineering distributed a software package that would parametrically generate dxf files of thier PEM swage mounted fastener line. but it would generate them with different scale factors for the x and y! I called thier customer support to tell them and they said that they did it on purpose so nobody could use the package to reverse engineer thier parts! I tried to explain to them that it made the entire package virtually useless and that if they really wanted to reverse engineer thier parts all they had to do was either A: buy some and measure them. or B: scale the cad package with x and y factors that corrected for the distorion. But they weren't interested....