The ways of worshipping Allah The Glorious are different in different faiths like Judaism , Christianity and Islam. We take the way of Islam because it is the most authentic being practiced by the Prophet Muhammad (SAWA) who can not be compared with narrators of other faiths. Likewise, the prophetic Prayer (Salah) narrated by Ahlul Bayt (AS) who lived with him and knew the most about his practice is the most authentic. Non Shia ways of Salah are been narrated from different narrators who did not live with the Prophet, even some of them did not meet him at all, as well as the non Shia way Salah are contradicting each other that is why you find the ways of Salah in Sunni sects and subjects  are different. Even timings of Assr and Isha Salah is different according to Hanafi sect and Shafi'ee sect. The way folding arms during Salah despite being never done by the Prophet, but it is been done by Sunni different sects and subjects in different ways. With all the differences among Sunni groups which you can read about them in Sunni books like Bidayat al-Mujtahid and Al-Fiqh ala al-Mathaahib al-Arba'ah,Bhowanipore can you trust that their ways are authentically narrated from the Prophet?

Shia way of Salah is narrated from Ahlul Bayt, The most pious who lived with Prophet and saw him always praying

Wassalam.