Its funny -- out of all the corruption you see from Washington this one seems the most benign. For whatever reason this one gets almost the most constant press. Maybe because its the easiest to fix but isn't.
Lawmakers deciding what laws to argue against/for based on how much money it'll get them personally is a benign issue? It's a very hard problem to solve, when the people making the laws have to outlaw behavior that makes them rich, but it's a very worthwhile one if you manage to get it down, because then you'll again get politicians working for the people rather than against.
The GP is right. It's campaign contributions, career rolling doors, and direct payments that make them pick one law over another. Inside trading only let them directly steal money from the population with no strings attached.
The boundaries between corruption, lobbyism, incompetence and nepotism can get very blurry (sometimes even actually representing your constituents interests can look this way!).
But policy makers enriching themselves by insider trading are seen as corrupt by pretty much everyone.
What is the less benign corruption seen in Washington that you feel is most pressing?
Bribery or anything else that affects their lawmaking decisions is significantly worse because the impact is so much larger.
But there is a third option: They are making decisions based on what will move something the most - doesn't matter what, and doesn't matter which way, and doesn't matter for how long. Then they invest in that thing a bit before the decision becomes public that moves that thing.
Don't get me wrong, I think campaign donations or even more explicit bribes are a huge problem, too, but it is already insane to me that you would ban and prosecute "ordinary insider traders" and just let lawmakers do whatever. If presidents have to give up peanut farming, then asking for congressmembers to be utterly decoupled from stock trading decisions is only fair and sensible in my view.