Problem with top execs incarceration is that it's not good for economy and country in general (sometimes, not always). It's more beneficial to fine them and let them go working/breaking law further.

Yes, that's not fair, but it's logical.

Having lived for some time in another country, I've seen counter-examples too: when execs were incarcerated for minor things and mere accusations, effectively destroying the companies they've built, so hundreds of employees had to look for another job. Everyone's seen that fairness doesn't play well with pragmatics, and it's better to let them go even if they are guilty.