Why is cost benefits analysis hard?

Cost-benefit analysis is challenging because it often requires quantifying intangible benefits and costs, such as environmental impact or social well-being, which can be subjective and difficult to measure. Additionally, forecasts about future costs and benefits can be uncertain and influenced by various factors, making accurate predictions complex. The analysis also needs to account for discount rates and time preferences, which can significantly affect the outcome. Finally, the need for comprehensive data can lead to biases or incomplete assessments, complicating the decision-making process.