It's really hard to prove someone traded off of insider information if they make a decision to buy/sell for themselves. If they don't tell anyone else why they made the trade, you don't really have any proof that it was made off of material non-public information.
If a congressman is forced to ask someone else to trade for them, they might be careless and you might be able to find evidence via text messages or phone records.
The last time a U.S. Representative got convicted for insider trading, it was because he called his son to tell him to trade a stock that he had insider information on: https://www.justice.gov/usao-sdny/pr/former-congressman-chri...
Are you now in a position where you have to prove a negative? Are there people in prison right now because of exactly this type of occurrence, or is it so circumstantial that it's not even pursued unless there is additional evidence, e.g. you always buy $500-1k in stock but after this call you buy $10k in options or something.
The people who do get convicted are usually those who were being particularly egregious or who pissed someone off enough to rat them out. For example, Martha Stewart got convicted because her assistant (whom she regularly called a "little shit") decided to testify against her.
New barriers include: the actual work of moving money around to and from friends and family and directing trades, counterparty risks in doing so (e.g. sibling dies and leaves money to someone else or takes the money and runs), tax complications, or reputational risk if found to be violating "spirit of the law" that might harm election odds. There are surely more frictions and barriers like these that I'm not capturing.
https://wibc.com/154888/climate-czar-john-kerry-throws-wife-....
The point is repeatedly emphasizing that "personally" he doesn't have a plane meanwhile repeatedly using his wife's plane while being the "Special Presidential Envoy for Climate".
https://www.usglc.org/positions/special-presidential-envoy-f...