Keep in mind, too, when looking at laws concerning procuring and keeping any animals the likelihood of "escapees" getting established in the area. The Brown Recluse has been expanding in range for many years, and is now even documented up as far north as Salt Lake City Utah. The Brown recluse produces a necroptic poison that kills off the tissue surrounding the bite. The trouble is, about the only effective means of stopping the spread of the necropsy is to excise the infected tissue, leaving large wounds or even full limb amputations in the wake of what seemed like a minor bite (unless they've advanced the treatment for the bites since the last documentary I watched on it). Even spiders that are not as dangerous to humans as the recluse can make a big impact on the local ecology if they have no natural enemies and end up displacing native species. It isn't just "anti-spider" sentiment that fuels such laws, even if the laws seem a bit overzealous.

While we may be responsible owners and do everything in our power to make sure our pets stay as pets, other people are not so conscientious about such things and have no qualms about dumping an animal in the wild if they're tired of it, or do not exercise due diligence in making sure the animal is properly and securely housed. Consider the woman mentioned on these forums earlier that had all kinds of creatures free roaming in her house, including at least one tarantula as I recall.

Added note: If you keep a Brown Recluse and do end up suffering a bite, do not, I repeat, DO NOT subject the bite to additional heat. One victim on a documentary I saw was bitten by a recluse while on travel, and called a medical line to ask what to do about a spider bite. The person they talked to did not know that it was a recluse bite, and/or did not know the particulars of recluse bites, and advised to subject the bite site to a hot shower. The heat accelerates the necropsy. This guy still had a large, open wound on his back well over a year after the bite. For a Brown Recluse bite, apply cold packs to the bite site to slow down the effects of the poison and get to a hospital immediately.