Gerald Ford was last one to not give a concession speech personally. The story was he had no voice from campaigning. His wife gave it for him and seems so angry .. Or trying not to transform or something.
HRC didn't concede right away because she was incredulous that the states she lost didn't go her way. These are the ones Jill Stein wanted a recount on. I saw a theory somewhere that the Clinton campaign knew the fix was in with illegals being bused in, irregularities in voting machines and no id required in many places. When she didn't win she had to wait because she just KNEW she was going to win. BO called and told her to concede. Probably because it was looking fishy for her to wait.
https:// www.quora.com/Why-didnt-Hillary-Clinton-give-her-concession-speech-the-same-night-as-the-election