Why the heck are members of Congress allowed to trade individual stocks?

The idea that members of Congress and their spouses could trade stocks without eventually running into trouble, even unintentional trouble, is so ludicrous, only a nation with a high tolerance for political corruption would permit it. The problem is basic: It is almost impossible for federal legislators, if they’re investing in individual stocks, to not, at some point, at least look as if they’re engaging in insider trading.