Interviews can help, but it's only partial. Let's pretend to work in HR. We have a position open for a senior programmer with a generous salary. We get 100 applicants. Well, we could interview all 100 of them, but that would certainly take a long time. If we don't have credentials that we trust on any of them, the interview must be quite extensive. Microsoft's interviews last an entire day. So, in order to hire someone from this group, it takes 100 days of work (whether that's 1 person working for 100 days or 10 people working for 10 days, it's a lot of work). And that's basically just lost productivity. With salaries of $50,000/yr, we've spent roughly $20,000 to hire one person.
Now, let's say that we require a BS in Computer Science and we trust identity in out society (no impersonations). Maybe we can weed out many of them who are simply kiddies using Joomla. Beyond that, we could even discriminate by institution. MIT to the top of the pile please! And so on. . .
Identity allows us to trust the information we receive from other sources. When your buddy vouches that you're fun to one of his friends, that friend knows your buddy and accepts that premise. They don't need to test you - they've accepted the credential that your mutual friend has provided. Likewise, a degree from MIT in Computer Science vouches for you as a major league nerd. While an HR department should still challenge you in an interview, it can allow them to weed out those who have no one to vouch for them and allows for somewhat more relaxed testing.
Heck, I get most of my work based off my portfolio. If others can claim to be me, they are able to use the sites I've built as vouching for them.
In the long run, people who are forging are found out. Eventually, that person with the bogus CS degree doesn't know what they should know and they're out. But in the short run, there's a ton of waste. They're drawing a salary as they work slower and produce crappier code. If we are trying to be efficient, we want to eliminate that waste.
And funny you should mention it - when I got hired to Microsoft nobody asked for my ID (until the day they needed to send the stuff to the tax-man which is long after the job offer was signed). I'm pretty sure nothing chnaged since. So you see, it works well enough.
I can see the point for your portfolio, but this seems like more of a business trademark issue than personal identity issue.
Delinquency history. People screw up. I'm a big fan of forgiveness. At the same time, the state has an interest in knowing whether this is the first time you've been convicted of a crime of the 20th.
Self-protection. Yes, identity (can) protect you from the state as much as it protects the state from you. Without identity, the government could (conceivably) steal you away in the night. With identity, that becomes harder as your relatives have documents proving your existence.
Those are just a few cases. To address your issues: your name must be on your passport because while your home country may perceive you as no threat, another country might perceive you as a risk. Usually that's simply an issue of politics, but let's say that it's 2008 and you're an upstanding citizen so you just grab yourself a shiny new passport; 2009 comes and you rob a dozen banks; it's in the state's interest to be able to differentiate between your passport and the passports of others at all times and not simply make the ok/not ok determination at issuance. With driver's licenses, an SSN requirement prevents someone who lost their license due to several counts of drunk driving from simply applying for a new one under a new name - drunk drivers can pass the exam, but they still aren't people I'd like on the road.
For better or worse, we're becoming a dossier society. On the better side, people who shouldn't be able to escape their past have a harder time (drunk drivers can't just go to the RMV and pass a test). On the worse side, people can't escape their past even when it's not that important - and I would say that a lot of people create a lot of anxiety over the fact that they have such a dossier following them around.