The Real Reason Why The Saiyans Couldn’t Become Super Saiyans!
When S-cell amounts become high enough, triggers like anger and high power level will enable the Super Saiyan transformations. That is right, the golden aura, golden hair, and blue eyes were because of the S-cells in a Saiyan’s body. If you think about it logically, it all perfectly fits, right?
Now, if you see the Saiyans living on Planet Vegeta or the Saiyans living on Planet Sadala before it’s destruction, just think about their lifestyle. They were always at war, little kids were sent to distant planets to fight and kill other species. Other than that, they were always under control of Frieza or Beerus.
There was practically no one, who had the chance to grow their S-cells even if they knew about it. Take Goten and Trunks for example, it was also revealed that Trunks and Goten were able to transform into Super Saiyan easily because they inherited a lot of S-Cells from their fathers. They were born with sufficient S-cells.