Thanks to modern digital cameras, even casual snapshots are sharper, better exposed, and more vividly colorful than photos of old. But digital cameras can't work magic. They aren't good at figuring out challenging lighting situations, so it's up to you to choose the right settings.
Don't expect Photoshop to transform your overexposed snapshots, either—photo-editing programs can tweak and nudge pixels in the right direction, but they can't save a train wreck. The bottom line: It pays to learn the basics of exposure, and to apply your knowledge instead of just relying on your camera's Auto mode.