Riflescopes often do have an adjustment. Many fixed are "fixed parallax scopes" that are set for 100-300 yards. If you pay attention, they aren't really that "focused" per se at all distances. It is still a compromise. The more magnification, the more you'll notice it.

"Full time night woman? I never could find no tracks on a woman's heart. I packed me a squaw for ten year, Pilgrim. Cheyenne, she were, and the meanest bitch that ever balled for beads."