Times have changed as have perspective renderings. We evolved from hand laid perspective line drawings, to painted perspectives to computer generated perspective renderings to the stunning photo-perfect architectural renderings you see today.
What used to be a difficult process of perspective vanishing points and constant architectural revisions has evolved into a process that removes all of the perspective calculations from the artist, allowing more flexibility and creativity. Finished rendering are now more realistic than ever and are produced in less time. Clients can now make changes as needed to improve designs without the need to rebuild the entire 3D setup or recalculate any perspective settings, or vanishing points.
Each alteration to a rendering viewpoint is now geometrically re-calculated in real time, so the issue of perspective variations is now null. Further more software can now calculate lens distortion and other factors to ensure the images now fit perfectly into actual photographs.