Go one step further
let people complete a PC competency test (say, something simple from CompTIA a few steps even lower in level that A+ focussing on basic internet safety) Have this test cost a few bucks and be valid for say 5 years, though an independent authority not the ISP itself (so its portable).
b) If you have not passed the test, your home computer connection (and all computers used from that IP) are monitored by a NAC system, and each PC can't get online (except to a quarantined list of IPs like OS and Virus app vendors) without passing a simple security screening as any business PC does (is it patched, does it have AV, are the definitions current, has a scan been run within the last 14 days, is there a logon password set). This requires a NAC application to be installed on your OS. If you don't meed NAC policies, you'll be quarantined into a network segment that can only reach sites that can help you meet those restrictions (OS vendor, AV vendor, etc) until you do.
c) If you have passed the test, and proven yourself security aware, a setting in the NAC app lets your local machine MAC address bypass the screenings, (and you can add more MAC addresses online personally through your account admin page), and no software is required and your machine is not managed by NAC (but you'll still be notified if they detect an infection, and if critical you may be temporarily quarantined).
d) If you are quarantined, but absolutely have to get online anyway, you'll have to pay a fee to get 24 hour access if you are not in NAC compliance. If we detect a virus, that is repairable through current AV definitions, you may be put into this quarantine even if you are not subject to the NAC scanning rules (but only if it is a critical self propagating virus or one active in an active attack against other systems. Low threat viruses will only get you warned, not quarantined).
essentially, if you don;t know better, we "assist" you in making sure you;re secure. If you don't want the assistance, get certified to bypass it. You may be quarantined if you have a serious infection (but you can pay to temporarily bypass it, or provide a scan log showing you're clean and we'll call it a false alarm and credit you something.