Asking a why question about the government will likely never get you theanswer you want. As a special request I will humbly speculate as to the reason why agovernment agency takes X period of time to do Y. As a general answer which can probably be applied to any government agencythe agency has a finite number of resources only so many dedicated staffmembers who must therefore thoroughly review and approvedenyrequest moreevidence with regards to each applicationpetition received. The three months it takes for USCIS to process an EAD application for F1students on STEMOPT is actually on par with all other EAD application types.In fact USCIS for the past few years has been fairly consistent andreliable w the processing times for EADs in general. USCIS employs a dedicated team of officers to review certain types ofapplicationspetitions. I can only speculate that because each officer has amassive number of applicationspetitions to review it takes approximatelythree months for the life cycle of an F1 students EAD application to becomplete assuming all the required documentation has been submitted. IMHO three months is remarkably fast. This answer is not a substitute forprofessional legal advice....