It should be noted that this article talks about a pretty niche use case without really spelling it out.

Camera optics are generally designed not to exhibit this kind of distortion. As other commenters note, wide-angle lenses are ground to provide rectilinear projection where horizontal and vertical lines are straight. Further, if a particular lens does exhibit distortion, the usual solution is to measure the effect and construct a reverse mapping that can be applied in software.

There are relatively few situations where you have a distorted image taken with unknown lens, but where you have a regular grid of horizontal and vertical lines for the algorithm to rely on.