[Rutles4Ever]

One could then argue that there should be no life-without parole sentences, or even custodial sentences at all, because the hyperwealthy will generally be able to avoid the harsher end of sentencing for any crime.

Agreed, that could be argued as well, however, a longer prison sentence doesn't violate the inherent dignity of a human being in the same way killing him does. There's a big difference between being alive and being dead, and that's where the Church (at least) draws the line in its teaching.

[wideawake]

that's where the Church (at least) draws the line in its teaching

The Church has never held that capital punishment, in itself, violates the inherent dignity of a human being.