TKO OVER KO, WHATS THE DEAL?

Iv'e been around boxing for more years then I remember, what I have noticed in oh say the last 20 years is that a referee will count out a downed fighter, he will take the count to around 8 then wave his arms and the fight is ruled a TKO, why does he not just count to 10, at what point did they change this? Did I miss somthing? Same as when a fighter goes down and as soon as he does the ref waves his arms? Why not count? see if he can get up then stop it when he stands up, let him earn the TKO over the KO. Any information would be appreciated.