This isn't really true though. This is how the law used to work, until people did the research and discovered it let to absolutely loads of mad variation in outcomes, with people with similar offences getting totally different sentences based on random luck. Hence most countries not have pretty strict sentencing guidelines, with a bit of space for judgement on top (despite a lot of protesting from judges).

https://www.ubs.com/global/en/our-firm/what-we-do/our-brand/...

You should be able to predict the outcome of a court case if you have all the facts available. That's what fairness means.