Driver or cyclist, if you fail to navigate that intersection safely and correctly you will be cited (or injured or killed). How does requiring a license for cyclists solve this problem? You mentioned that driving without a license will get you arrested. This is true, but only after you've committed a violation, unless your country has random driver's license checkpoints (mine doesn't). We can already cite cyclists for moving violations today. Licensing doesn't change anything.
Realistically, every 5 year old knows what the colors on a traffic light mean and what a stop sign tells you.