Because emails were considered a low level security risk. She didn't do anything w/ her emails that other politicians did before her. The difference was, she got caught on the cusp of a rule change and failed to comply. She apologized for the mistake. The FBI investigated, backed away f/ pursuing it having determined no breach in security occurred. The history on Hillary is the reps did everything in their power to smear her. When the smoke cleared, she never even faced a grand jury let alone indictment or conviction. Reps even admitted to grandstanding as a means to reduce her poll numbers. Trump vowed to lock her up. Even the most powerful man in the world cant find wrong doing that didn't occur.