From government perspective the prosecution with jailtime will mean lengthy court processes with an army of lawyers. Lots of costs for government and headache for the government officials.
Instead if you just impose a fine, the government will actually get lots of money with little work and headache, and everyone involved will be moderately happy.
> From government perspective the prosecution with jailtime will mean lengthy court processes with an army of lawyers.
You're missing the point.
The US government has no desire to try SEC and/or white-collar cases without almost certainty that they will win. They don't really care about deterrence - losses tarnish runs for political office later. (You can watch "Law and Order" to see how that works at the city and state level.)
This is a subtle form of regulatory capture that greatly favors the largest companies. Fines look like a govt. win without the risk of a loss.
It's so bad that federal prosecutors mailed companies to not fund legal defenses for executives charged with a crime, in order to win more cases against defendants who couldn't mount a vigorous defense. (There are even some court forms that ask where you got the money to pay your defense lawyer.)
The Countryside shutdown was a multi-billion dollar debacle for the US government. Countrywide CEO Angelo Mozilo basically walked away without legal repercussions after it cratered. He even gave discounted mortgages to politicians to ingratiate the company in Washington. Who's going to indict their mortgage holder?
Instead if you just impose a fine, the government will actually get lots of money with little work and headache, and everyone involved will be moderately happy.