> How would you intend to enforce this?
By law.
> Declare a law that no banker must be paid more than than the current highest government salary?
No. Simply have a law that employees of a bank that has been deemed "too big to fail" will be regarded as public employees (which they effectively are) and are paid according to the BAT, the Bundesangestelltentarifvertrag, in Germany. Other countries will have similar official regulations as to how public sector employees are paid.
"Too big to fail" = "Too big to bonus"
> Who defines a "banker"?
Employees of a bank that has been classified as systemic, as too big to fail. If the risk is public, the pay is public. If you want private pay, your bank must be small enough that the public does not carry the risk.
> ..does that same rule apply to the CEO?
Of course. Especially to the CEO.
> ...without thinking it through.
Just because you haven't thought this through doesn't mean I haven't.
> Credit Suisse is a poorly-run and incessantly corrupt company
This isn't a singular problem of Credit Suisse. 2008 was just the same, only (so far) on a larger scale. I am usually extremely loath to declare simple/moralistic causes for what appear to be complex and systemic issues.
But in these cases, it really was that simple. The bankers knew that it was a sham. They kept the sham going because they wanted to get theirs before the music stopped. When the music stopped the public had to bail them out. And the bankers were still rich. Because profits were privatised and risk was socialised.
Fool me once, shame on you, etc.
See also: https://en.wikipedia.org/wiki/Moral_hazard