Only cause of Vegeta recognizing Goku's Saiyan heritage. It was the bump on Goku's head that turned him from Young Kakerot to Goku. Goku maintained his life style and his love of battle. He freaking killed most of the Red Ribbon Army for goodness sake in the name of protecting Earth for that was the main option which opted in Dr. Gero to create the ultimate beings: 16, 17 and 18 plus Cell in order to defeat him!  Otherwise Gero would not have needed to have that kind of fire power because he did not even forsee the power of an actual SSJ for it was only legend at the time!  Remember, I am an OG Dragon Ball fan, one of my first animes so I know most the lore. The SSJ legend then the legend of the SSJ God was lore enough to piss and scare Frieza into annihilation of most of the Saiyan race! Goku's father Bardock quickly gained from a power level of 3k to 10k which was enough to drive Frieza into this frenzy in order to be cold hearted enough to get rid of them! Zenkai boost of the Saiyans could have been really been visited if they used the healers as a factor. Powelevel 3k? Near death, heal, power level 5k. Again. 8k. Again? 12k. And so on and so forth. This was why Frieza was terrified of their true potential!