Judges are regulated because they can't bring forth cases. Only a prosecutor can. The prosecutor is regulated because they can't make a decision, only the Jury can (and the Judge handles meta-decisions). The Police cannot execute you, they can only had evidence over to the prosecutor.
"Government" is about designing a system of different people, doing different jobs, doing different checks and balances against each other. Anyone who thinks "Oh, X just will self-regulate" is looking at the worst of strawmen.
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That being said, in many cases we don't know what kind of system should exist to move forward. In these cases, having the free market self-regulate while we figure out issues is probably better. Later on, we can write laws that benefit everyone once we understand what the heck is going on.
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I don't think our banking system is doing much wrong. Yeah, I'd prefer if SVB didn't take a bunch of people's money, but the shareholders (and maybe even the bondholders) are going to be wiped out by this debacle. FDIC taking over in the case when things get bad did work, I just personally disagree with what the FDIC did.