In the USA, unemployment is based on a periodic, 60k household survey. You may not have ever been contacted but that's just the nature of sampling. It's true that some countries report unemployment as those who are actually registered as unemployed, but that's not best practice (and a good reason to be careful comparing country unemployment rates)
I agree it's a bad outcome that someone who gets so fed up with the labor market that they stop looking for work no longer counts as unemployed, but that's why we have labor force participation (and why imho that should be reported in headlines along with unemployment, after adjusting for age and education)
You can read more on the US system here - https://www.bls.gov/cps/faq.htm#Ques3
I agree it's a bad outcome that someone who gets so fed up with the labor market that they stop looking for work no longer counts as unemployed, but that's why we have labor force participation (and why imho that should be reported in headlines along with unemployment, after adjusting for age and education)