And yet people still stole stuff. Does that say something about deterrence?

If you're stealing to live, the threat of being executed is just an alternative ending.

In 'The Commonwealth Of Thieves' Tom Keneally notes some people were committing offences with the express intention of being sentenced to transportation to the penal colonies in Australia. Apologies for the secondary source.

As you probably know, some were only transported temporarily and returned to England at the end of their servitude.

There's very little reason to think that the death penalty was ever an effective deterrent.