That article is a week old, but i didn't know anything about smeets living in Holland for the first 13 years of his life.
he's been able to represent as australian for his whole career
Robert Smeets is Dutch, speeks with a dutch accent, not strong but it's there. He has been able to compete under Australian Flag as he is a resident here, that said though, you can not represent the country at eg Olympics, Davis Cup (basically where it is countries competeing and not so much the individual..) if you do not hold a passport, you cannot hold a passport if you are not a citizen. So therefore Smeets has been able to compete on the tour as Australian but it was not until now that he could be considered for davis cup bc of his non citizen status.
Carsten ball however is Australian by birth since his father is Australian, but he has never really lived in Australia and speaks with the broadest american accent. they are all aussies, but to me smeets seems more aussie to me. Ball has played under US his whole life until AIS offered him their services. I am sure if USTA offered him those same services he would still be under US flag.
BUT good luck to them all, may the put Australia back in the World Group. It is a daunting task but not at all impossible!