Units of measurement (UoM) libraries are mostly used to appropriately encode unit variables and convert between them in a type-safe manner. Approximately 3700 functioning unit measurement libraries exist on the web, indicating that the wheel is being reinvented time and time again. Previous research has postulated that too much diversity, lack of code sharing and duplicated efforts are discouraging adoption, yet more remains to be known. Three developers and a scientist were interviewed and 91 practitioners of varying experiences from online forums were surveyed to explain their dissatisfaction with UoM libraries and possible reasons behind the lack of adoption. Our findings range from insufficient awareness of these UoM’s, to development processes that exclude unit information through to specific performance concerns. We conclude with recommendations to UoM library creators stemming from these points that could help alleviate the problem and lead to an increased adoption rate of methodologies that support unit annotation and checking.