That would be because the typesetting algorithms were created in 1081 and used byeveryone. Not to mention that the Windows printer drivers control the output to the printer.
Another blogger noted yesterday that the "th" lined up perfectly when you printed to paper, but not when you used a screen capture. Such differences are to be expected.
I hate to say this, but one of the reasons magazines use Apple computers and Quark Express is their ability to exactly match screen images with final printout. Little things like the subtle misalignment of the "th" can drive graphic designers nuts.
make that year 1981.