I agree that it isn't about rehabilitation. And to a certain degree it definitely seems our system is geared towards retribution. But study after study[1] has shown that an individual's perception of the likely punishment (e.g., prison time) doesn't deter crime. Rather, an individual's perception of the likelihood they'll get _caught_ seems to be the main deterrent.

This is a really interesting & related read.[2]

[1]https://www.journals.uchicago.edu/doi/abs/10.1086/670398

[2]https://undark.org/article/deterrence-punishments-dont-reduc...