The comparison was that for some it may be excruciating and that others it may not. Maybe a tattoo isn't the best analogy, but their main point is apropos to the idea that understanding the experience of others may be difficult when there is a wider range of experience than many want to admit.

I don't believe that was the intent of your parent. The 6 hours of tattooing was instead a scenario they have personally experienced where they have also observed others having wildly divergent experiences from themselves, despite the same inputs, and are using that to bootstrap a framework for understanding how wildly different others' experiences with hunger might be from their own.

It definitely belies a level of privilege that some people must intentionally seek out discomfort or pain in order to begin to even approximate the agony others are inherently forced to live through. I don't believe privilege is itself a moral failing, or we're stuck with whole categories of 'original sin'. It's what objectives its used to enable that potentially indict those that possess it.