While advances in technology contribute to the decline of sports referees in the coming years - instant replay is more reliable than the naked eye in assessing certain plays on the field, for example - there are multiple reasons for the projected decrease.Full-time referees earned less than $25,000 in 2016, according to an infographic by Ohio University; they also reported experiencing physical and verbal abuse from angry fans, and limited mobility in terms of job prospects. All this means that as older refs retire, fewer young ones are ready to replace them.