How much benefit should someone get from laws past before it is wrong? For example, if someone had an index fund and passed a law that made the entire market go up, is that wrong? What if its an index fund for a specific sector, and the law helps that sector? What if you own a car dealership and you pass a law that promotes more auto sales?
Before I answer you, let's be clear that you're addressing a different issue than what is under discussion here. We're talking about a bill which attempts to prevent conflicts of interest from arising in the first place. You're asking me whether we call something "wrong" in one situation or another. The problem with this entire line of inquiry is that whether something is "wrong" depends on
intent. Which provides a short and simple answer to your question: it's wrong whenever private financial gain is the primary motive behind the policy undertaken, regardless of the specifics, meaning that
any of your examples could be wrong or not wrong in the individual case.
Yet this intent is difficult to impossible to prove. A person could financially benefit from a policy they enact but that might be incidental to their purpose of trying to promote the general public interest. Or not.
Except in a rare case where a policy benefits only one specific company that the person in question has an interest in, it's nigh impossible to ever prove the bad intent. Which is precisely why this is a bill about prevention of conflict of interest situations, rather than one which imposes penalties for unethical behavior after the fact. The way you've framed your questions suggests you may be erroneously assuming that the things this bill seeks to prohibit are situations which are unethical by definition. It is not. Stock ownership while in office isn't unethical per se. Rather, it creates a
situation where one is
tempted to act unethically.
Accordingly, I will address your specific scenarios through the rubric of what red flag situations it makes sense to prevent, rather than your formulation of what is wrong or right. The idea behind a preventive bill like this is to identify the most likely situations where an official might be tempted to act for personal gain. This bill does a pretty good job of that.
It excludes general index funds, which makes sense. Ownership is too dilute in that circumstance to provide much temptation, and in a very real sense, everyone in the country, regardless of what they do or do not own, has at least a potential financial interest in the general state of the economy.
Common stock ownership and targeted fund ownership, yes, those are situations where there is too much incentive to act for private gain. It should be prohibited so that we don't have to later wring our hands and speculate as to whether the official in question acted with bad intent or not. And even where there was no bad motive, there is still an appearance of impropriety which undermines public trust in government.
Your car dealership example is also a red flag situation, but from the standpoint of federal law, we're best addressing it as stock ownership rather than saying that no business interests are permitted whatsoever. That is because stock ownership, which is generally ownership in big companies which do business nationally, is more likely to corrupt public policy at the federal level than does ownership in a small business.
That kind of issue is better addressed at the state, or even the local, level. I'm talking about situations where someone on the town counsel promotes an ordinance which would spend money to improve road access to only one business: his own. But you likely can't address it even there by prohibition of owning the business. Having to sell off a small business which may be your entire middle class livelihood in order to serve on a town counsel is a very different situation than requiring a billionaire to convert his stock into cash. So in the case of small business ownership, prevention is simply too harsh. Fortunately, on the local level the issue can be better addressed through punishment after the fact, because local laws are often very minute and specific in scope (like my road access example), and hence it can be easier to make the case for bad intent than it is with federal laws which are generally much broader in scope.