"convictions for those involved in sub-prime mortgage-backed securities?"
You are right - even the situation was a bit different since most of the practices that brought to the collapse were not illegal because actually the laws protecting from the were lifted, due to pressure from bankers lamenting they could not grow enough.
And it is true that when there are many, many culprits, including the government, its agencies, and the politicians, nobody has really interest to get to the bottom.
Biting the hand that feeds IT
