CD volume levels


I'm a bit confused by various recording levels I've found on CD's. While most fall in a narrow range of mastering/pressing levels, every so often, I'll run across a CD that was manufactured with a really hot (loud) level, while others are rather anemic (soft). I'm not talking about compression or limiting on the master tape, just the absolute mastering level on the CD. While I understand the physical limitations of cutting vinyl (a combination of science, art, with a little voodoo throw in for good measure), why would there be such a variation in the digital domain? Are there trade-offs with different levels when pressing CD's, just as on the analog vinyl?
fatparrot
No problem Phild. I do want to add one thing though. There are very few, very talented mastering engineers that really know their rooms/monitors/and especially how to use their gear, that can manage to make a heavily compressed and limited record still sound immensly involving. If my record would have to be squashed inorder to compete in the marketplace, I'd be able to sleep at night knowing it came from their capable hands
Would you mind listing them or e-mailing me with their names?? I may be looking into mastering a rock band recording sometime soon. I'd be especially interested in any in, or near, Chicago. Thanks again!