The people doing it do not trade themselves. And the SEC does not have a list of all current and former employees of the company (only certain officers have to

The people doing it do not trade themselves. And the SEC does not have a list of all current and former employees of the company (only certain officers have to actually report with the SEC). People who do this are not idiots...most of them do not get caught (selection bias, you only see the people who got caught, there are individuals who have made $100m, $200m doing this...never been caught or charged). Also, the way they do this is by examining trading patterns. The SEC is 100x better at this than most other countries. Insider trading prosecutions are very rare outside the US (not just because it is hard to catch, it is very hard to win insider trading cases at trial). It requires a fairly sophisticated approach to uncover suspicious trades (every day, billions of trades, millions of securities, you have no idea who works where, you have no idea who their family is, you have no idea who their friends are...not easy).