Arab Shias venerate Ali too. The matter has nothing to do with nationality & race, it's just wrong religious beliefs which the Iranians adopted recently much later than Arabs or even Turks.
I'm aware. I just find it strange that Iranians would jump on that veneration train and venerate an Arab other than the nabi (SAW) who sort of transcends nationality as a prophet. They worship the guy and care so much about some dispute over who should be Caliph that happened between people who were just as human as them and not at all prophets. It's just odd.