Yeah, if waste management was as viable as proponents claim, places like Hanford [0] would already be an inactive site with a memorial park on top.
Whether it's technology, economics, or politics, clearly the state of the art is deficient because we currently have persistent deficiencies.
There is a difference between “something can be done correctly” and “something is likely to be done correctly.” Nuclear advocates I’ve read tend to argue the former - it’s possible to have safe reactors, it’s possible to keep the waste sequestered safely, there’s not a technical reason why nuclear is inherently unsafe. Skeptics tend to be making a different argument - not that it’s not possible to do things safely and correctly, but that in our current late-capitalist milieu, it’s almost impossible that we _will_. It’s not an argument about capability, it’s an argument about will and what happens in bureaucracies, both public and private.