I'm amazed that this year's IndyCar season has had multiple races without any cautions. In this article, Alexander Rossi's explanation is that none of the drivers are giving it 100%, just 85-90%, and that's why there haven't been any cautions in multiple races:
https://www.indystar.com/story/sports/motor/2025/05/02/indycar-cautions-free-streak-alexander-rossi-car-marcus-ericsson-alex-palou/83410253007/