The business judgement rule and limitation on directors' liability restrict shareholders' ability to get the courts to order reimbursement for the payment of these expenses or the loss in share value. Large institutional investors are too large to sell out of every company that is a possible target of this investigation. It is impossible to maintain a diversified portfolio and sell out of every company that enters into contracts with the government. Even if they would or could, by the time the disclosure is made, the impact on the stock has already occurred. Selling out is only mitigating damages.
Litigation is long and expensive, and the shareholders again foot the bill for both sides.
The exercise of the other rights of ownership presents a more constructive option. But corporate managers resist accountability to shareholders, especially since the volatility of the market for corporate control has created additional incentives for entrenchment. And one way to do that is with a corporate structure that promotes accountability to shareholders. For example, I can not think of a case where shareholders have voted out the directors of a company that violated the law. Unless someone comes in with a well-financed contest for control, they do not even have a choice.