Modern machines and energy allow things to scale and be decoupled from human productivity enough it’s easy to forget - but it used to be, a hand not helping make food and helping it’s neighbors, was a hand hurting them. In real, concrete ways.

Back then, no one had the infrastructure or wealth to deal with putting a bunch of assholes in cages and feeding them regularly until they ‘behaved’. Usually anyway.

Hell, unless the cages were intentionally horrific, that would often be a step up on most folks day to day living conditions anyway.

So make an example, and make it a spectacle - and cheap. Hard to beat an execution on that front!

A very different time and place, but in early medieval Iceland if you poked out someone's eye, that someone now owns your corresponding eye. Then you can together come to terms on whether the eye should be also poked or if you can agree on a price to buy it back.

A more statist example, at times in ancient China the law code had execution as punishment on basically every crime that the state got involved in at all. But most of the condemned were not executed, but eventually had their sentence commuted to internal exile (into some other part of China).