Hello Kiesel: always welcome.
IN CAMERA CORRECTIONS
Almost all modern cameras apply in camera corrections, so, what you get in the photo file (jpg and raw too) is actually a cooked version of the actual image.
If you apply a raw converter made by a third party without any input from the manufacturer, you will see how your photos actually are, and this will make you feel cheated some times. The same happens when you use legacy lenses, just glass and metal, we are so used to "nice things" that the true is dissapointing (Still there are honorable exceptions)
To manufacture lenses to perfection is imposible, and it is much more cheap to correct the image than to correct the lens. For this reason, camera manufacturers have flirted with software makers so well that many cheap lenses today appear to outperform first-class legacy glass.
In camera corrections are generally well implemented, but they correct the bigest part of the problems. I guess the corrections are generally made not considering particular defects of each serial#, like eccentricity, and more likely a supposedly symetrical model is probably applied around a supposed center of symetry in the center of the sensor and not the principal point actually.
OUT OF THE CAMERA CORRECTIONS
Theese can be applied with software tools (lightroom, ACR, photoshop, ptlens,etc.) that are created to make the photos look nicer (straighten lines, no barrel or pincussion evidence, etc) but again, if this corrections are not made with rigurous math model then they can turn a more or les evident barrel curve into a very straight "something" that is not a straight line. This weird "something" is often very hard to fit into photogrammetric formulae and that's why Out-of-the-camera corrections are not recommended unless are applied by means of photogrammetry software. In the best case you could obtain the same accuracy with very well corrected images as with their corresponding unprocessed ones... but is more likely you get worse results.
GEOBIT