White collar crimes are still prosecuted. The Feds still go after insider trading.
The facts for the various senators are not all the same, and from what I understand many, if not all, have pretty good defenses, including: don't manage their stock sales, in blind trust, purchase/sale activity no different than any other time, etc. Made for a good headline, and may snare one or two cheats, but probably isn't as big a deal as the media and online echo chamber would have us believe.