Despite Congress' general dysfunction, this seems like a problem that could feasibly be solved. It would make most Congressmen of both parties look good to pass a bill that e.g. restricted sitting members to index funds/mutual funds/etc.
https://www.currentmarketvaluation.com/models/s&p500-mean-re...
Yeah, sometimes people can break laws and not get caught. But that's no argument against laws. Some congressmen might be able to hide their investments, but sometimes they'd get caught and plenty of them would not take the risk.
If you work in a financial company which does trading often times you are very restricted in what you could do. You also have to report all of your accounts plus close relatives accounts.
And if you have an insider info and give it to someone else, no matter how remote from you it's still against the law to trade based on that and it's not "fully compliant with every letter of the law"