I definitely see this as an User Experience issue on the Brazilian website rather than an actual security or privacy issue.
While commercially speaking they could just get a Verisign cert, I think a better solution could be for browsers to include government CAs - in my experience they actually verify your identity way way more thoroughly than any commercial CA.
Also, since there are varying levels of trust, perhaps browsers should reflect that instead of a red/green metaphor?
However, from a security standpoint whatever security is provided by SSL still stands if one decides to add the 'untrusted' certificate on the first visit.
Why anyone should trust a site certified with one of the cheaper Comodo certs, and not trust a self-generated cert is beyond me. Now one of the things I do is
encryption software, so my ideas are a bit different from an average user. But there are a few underlying issues with SSL as it stands, and this is just one ramification.
SSL is supposed to be based on trusting CAs, but today it really is about trusting your browser's judgement about inclusion of root certificates into browsers. When GoDaddy got into the SSL certificate business they acquired a (IIRC) defunct CA just so they were grandfathered into a lot of browsers. ïOn the other hand browsers do not include root certificates of national CAs by default, and Governments don't seem to be in a rush to pay MS or request FF to include or link their certs in browsers.
The commercial CA business is a goldmine that verges on a scam - at least Verisign will ask you to fax over some documents to them, but a few CAs only care for their fees.
Lastly, I'm sorry about the appearance of xenophobia in this discussion; but that is a fundamental psychological and historical raison d'etre for visas and border controls - so there.