> There could be 0% unemployment and anyone could find another job easily
Technically, 0% unemployment would mean that you can't take another job, as you transitioning into another job would create frictional unemployment, which would mean that the unemployment rate would not be 0%.
In practice, somewhere around 3% is usually considered full employment. The 3% are those in the process of changing jobs.
> Technically, 0% unemployment would mean that you can't take another job, as you transitioning into another job would create frictional unemployment
Transitioning to another job only creates frictional unemployment if there is a period where you are out of work but looking for work. Otherwise (e.g., if you find a new job before leaving) if you have a break from work as part of transition, it creates a frictional exit from the labor force, not frictional unemployment.
But 0% unemployment is hard to imagine if employers can terminate workers without first finding them acceptable replacement employment.
Technically, 0% unemployment would mean that you can't take another job, as you transitioning into another job would create frictional unemployment, which would mean that the unemployment rate would not be 0%.
In practice, somewhere around 3% is usually considered full employment. The 3% are those in the process of changing jobs.