Depriving them of the ability to work and be a productive citizen. Depriving them of their existing assets (fines), and as stated by Manning and others, that grand juries have tended in the past to victimize those they call as witnesses.
[0]: https://en.wikipedia.org/wiki/Cruel_and_unusual_punishment
Unfair? Unnecessary? Unfitting of the wrong? Those are all things I don't know enough to really say or discuss in an educated manner.
Why would I assume you meant the colloquial "cruel" and not the legal "cruel" here? Perhaps you should edit to clarify if your intent was the former as opposed to the latter.
Perhaps you should also edit to clarify your intent.
This is the same line of reasoning Alex Jones uses to justify his conspiracies. "The government had Project Northwoods, why isn't [conspiracy] likely?!"
I personally don't like death penalties (due to their misuse as a political tool and the general high error rate of judgement) but I believe proper lethal injection fits perfectly within the bounds of not being cruel nor unusual.
So, if someone said that lethal injection was more humane if administered in direct sunlight while the injectee was hanging upside down due to blood movement some-such... assuming they were telling the truth about the efficacy then it'd likely pass the 8th amendment.