This is because these names were registered before the normalization standard was implemented. Many people seemed to take the chance on the decision that was then in limbo; that the normalization would include certain characters.
→ ENSIP15 is the standard
There are a few threads here regarding the topic. They are quite lengthy. But they offer comprehensive discussion about implemented standards as well as resources to tools.
ENS Name Normalization
ENS Name Normalization (2nd thread)
DNS Collision
On-Chain Normalization
Hopefully this helps with anything else you might come across. If not–or require more in depth technicals–@raffy is the mastermind.