Flying and driving are slightly more socially necessary than capital punishment. More importantly, all deaths related to those are accidental. It's a bit different than willingly killing an innocent person.

 

You can appeal life sentences. Death sentences, once carried out, are obviously final.

 

But I thought lengthy and expensive appeals were part of the problem with the death penalty? The real problem here is the small margin of error jurors may have when they convict someone beyond a reasonable doubt, isn't it?

 

Look up the differences in the appeals process between life sentences and death row.

The real problem is that the death penalty is the gov't and our society killing people. It's not an individual (humans are prone to violence, and individually you can't help that). It's not a war (where one group needs to defend itself or attain something from another group). It's our society and government reverting to the exact animalistic instincts that those institutions are designed to resist and avoid. They even force all of us as a whole to pay for it.

 

Only because it is a recent social development that it wasn't far and away a majority of society that favored the death penalty. It's less than a century since it could even be a debate, let alone resolved that society as a whole does not wish to continue with capital punishment.