The Problems With Immortality

Hypothetically, how long do you suppose would someone who is immortal be able
to live a normal life before being found out in modern society?

(As to what defines immortal, I'm assuming that telomere wear and disease
would be covered, but it is up to our hypothetical immortal to remember to
eat, breathe, and avoid fatal bus encounters. So if you are the seventh son of
a seventh son, try to avoid making contact between a broadsword and your
neck.)

A hundred or so years ago it would be very easy for an immortal person to walk
into a village, claim to be 20 years old, stay for a few decades, then move to
another town and do it all over again. In the U.S. you could simply move to a
neighboring state and you were basically anonymous since state databases
rarely communicated with one another.

Even as recent as 50 years ago, there were many gaps in government systems
that were especially susceptible to human error. Spy novels liked to suggest
finding an infant's grave, obtaining the child's birth certificate and using
it to apply for other ID like a driver licence, because it was unlikely that a
death certificate for a child that young would have been filed. But those
loopholes have been closed off over the years.

Now, however, any arrest will enshrine your fingerprints and DNA in a national
database forever. If you're arrested again 90 years later, questions will
arise.

As for employment, there's a gray market for jobs but I doubt you'd want to
spend eternity mowing lawns or squirting the guac bottle at Taco Bell. The
super rich can circumvent a lot of the bureaucracy and someone who has lived
for centuries may well indeed be super rich. Bribes to doctors and other
officials to generate documentation could go a long way, but great wealth
brings notoriety and that's the last thing an immortal would want.

Of course one could just not try and hide it and take your chances, since it's
not illegal to live forever, and hope that you can defend yourself against the
government goons who will inevitably show up to take you in for "further
study".