During my (ITIL) trainings, I noticed that participants lack the knowledge about ITIL, its purpose and applicability. That's one of the reasons. Additionally, they think „it's complex and complicated“. They also don't know where to start. Training fixes some of the issues. Additionally people think they need a lot of human resources and they don't see benefits. There are some additional challenges that companies face. See the article „5 excuses why IT organizations avoid ITIL implementation here: https://advisera.com/20000academy/blog/2015/08/25/5-excuses-why-it-organizations-avoid-itil-implementation/.