It is important to remember, in the USA, that there is no law that requires a office holder to concede an election to their opponent. Public offices are held for specific lengths of time. If the incumbent looses their bid for reelection, they serve out their term, and then the newly elected office holder is sworn in.
In the USA presidential elections are recounted once, candidates can request recounts but they must pay for them. Once the States certify the election, the electors of the electoral college cast their votes, and a winner is declared. The transition between presidential administrations has zero to do with conceding. That is just ho it is.
Egor