Only USA people are arguing against it be cause of national pride, it's the "planet" they had discovered. Among astronomers the consensus is established.
You overestimate how many of us even know that. It was probably mentioned in school I guess, but this is the first I remember hearing it. I did do kindergarten to 2nd grade in a different country though.
Why do you think you were taught about it? What you learn at school is heavily influenced by the "national myth". It's most visible in your history lessons, but science is also impacted, it will be biased towards your culture's scientists and discoveries. I am observing that in Europe too, I'm not saying the USA are worse on that.
That's why I assume ir was taught, but as I mentioned I have no memory of it, so it wasn't taught that strictly. I went to school in a county that had schools named after "Stonewall Jackson" and the like, so I'm sure biases were baked in.