Pay is only one part of the total compensation pic...

Pay is only one part of the total compensation picture so comparing pay only is not looking at the entire salary. There are other factors too that make salaries vary per environment. For instance a personal handling HVAC in a hospital environment is different than HVAC in an office atmosphere. Looking at straight salaries may cause the person working in an office to feel they are underpaid wherein actuality there are other factors that come into play. Salary knowledge is not bad knowledge yet it is not a full picture.