There was a time in England that theft was punishable by the death penalty. When I was younger, I learned that changed because of behavior of criminals under incentives: when stealing the bread is punishable by death, you may as well kill the baker too, to cover your tracks and maximize survival odds.

That might be true, but the more specific issue England (specifically, London) ran into is that trials for theft were trials by jury, and the jury (staring into the eyes of the accused and recognizing a boy of only sixteen in the box) increasingly found thieves innocent rather than having to have the death of a child on their conscience. Facing a situation where theft was functionally un-punishable by law because no jury would convict on a crime like that with a death penalty attached, the merchant class petitioned to have the punishment stricken from that category of crime.

This is, incidentally, why "right to a jury of one's peers" and "right to face one's accuser" are baked into the US Constitution... A lot of actual justice happens at the intersection of the law and the humans who must execute it.