The drop rate is a state of conversation pretty regularly on online discussions, for example, the "Rocket League" subreddit. So Rocket League Items perhaps the designers needed to make it all the more obvious to facilitate the fans' theory.
The drop rates for the "five Customization Item extraordinariness levels" are underneath, civility of Psyonix:
The odds of accepting a Painted or Certified ascribed things are lolga 25%.