Which is just because not only those that profited from slavery paid taxes on those profits which improved the lives of all those who lived under the same state, they also individually used those profits in philanthropic projects (schools, hospitals, poor houses) that have benefited the public as well. On top of all these, just the injection of wealth that stemmed from slavery and other exploitative practices into the economies of these countries that practiced them had a positive effect on the growth of those economies the benefits of which (lower unemployment, higher incomes etc.) being reaped by the general public.

All of these have a compounding effect that positively affects the lives of the people living in that place (wherever that is) in the current times so even though they don’t own slaves now or their ancestors have never been part of the slave trade it is fair that they should be a part of paying reparations.