1. My ISP isn't authorized to carry fully automatic, high rate-of-fire weapons.
2. My ISP cannot, with full authority of the law, bust down my door at 2:17 a.m., force me down on the floor at gunpoint, and confiscate anything in my house that looks remotely computer-related. And not give it back. Ever. Or maybe in pieces, if I'm lucky.
Geez. If those reasons aren't enough to convince you, I'll take thirty seconds of thought and come up with another ten reasons.
Oh, and I speak as a system administrator with over five years of experience, in production environments, at corporations with eleven digits in revenues. While I've had full access to all data on the systems in my control, I've never had a whit of control over anybody's life, or freedoms. *That* is the difference.