I think it rarely prosecuted because prosecuting is risky and expensive. You have a complex technical issue few people truly understand, you are probably not 10

I think it rarely prosecuted because prosecuting is risky and expensive. You have a complex technical issue few people truly understand, you are probably not 100% sure there was actual fraud, and there is always a real risk that the court makes the wrong decision. And unless the situation was completely clear, you know that the prosecution will discourage honest researchers from studying topics that could be controversial or have a significant real-world impact. As for class action lawsuits, the researcher who published the fraudulent result is the wrong target. The responsible engineer is not the person who designed the product but the person who approved the design, and the responsible scientist is not the person who published the result but the person who made decisions based on it.