Does this guy have a passport? Then he has a mailing address.
He claims to work. Then he pays taxes. In which country? he has a mailing address.
At 17, I'd bet good money that his mailing address is also his parent's mailing address. This is a gap student having fun bouncing around Europe, about as nomadic as any other backpacker.
But I don't really understand how this small legal detail would change the whole character of his life experience, in any case. No matter what is written in his passport, he spends the whole year in a train.
Look at the "Van life" trend. The people are forced to live in their cars/vans really do not appreciate those who glamorize it. It is not an easy thing.
With the upgrade to "Registered Address" it costs a whopping 79.95€/month though, so it is not really a really an option for me. But good to know that it exists.
I spent 2 years driving from Alaska to Argentina all on tourist visas. I spent 3 years driving around Africa all on tourist visas. Technically I could have done that without paying tax anywhere, though I continued to do so because I was working towards permanent residency in another country.
I now have a passport from a country I've never been to. I've renewed my passport from the country I was born in three times without going there.
I only need a mailing address to actually pick something up, and I usually use a friends address, or even that of a hostel or campground.
I'm curious, what country let you work towards permanent residency without you being physically present in it? (Sounds like you were driving around different places at the time)
BTW I spent the last 15 mins enjoying your blog, particularly the entries on Tanzania (I grew up there). Glad you enjoyed your time there :)
At that age he's also mostly included in his parent's insurances, so one less thing to worry about. Taxes are deducted automatically from his wage. And to receive the wage he just needs a bank account.
but anyhow, you could plausibly get by with not paying any taxes by continuously moving countries. The real question is to which bank is the payment being made? If your an employee you'll probably have your income reported. you could skirt that, somewhat, by being a contractor, but even then, to which business, or to which bank account is being made?
Anyhow, none of that precludes him from being a nomad. it seems you have more of a bone to pick with the choice of the word nomad, which descends from 'noman' or more modernly 'nobody'. I think it has more to do with a lack of permanent community than a lack of a mailing address.