Why are there so many uncertainties and differences in the performance of Salah?

Why are there so many uncertainties and differences in performing the Salah? One school says this, another says the other, Some group of people believe this to be true, the other believes something else. Prayer is the second most important pillar of Islam. Why is the subject of Salah mentioned so vaguely in the Qu'ran, I mean, shouldn't the ways and methods of performing Salah be mentioned clearly in the Qu'ran or rather even somewhere else like why didn't the Prophet Muhammad (SAW) decide to write down the rules and regulations of Prayer and preserve it? Instead, we are to be depended on narrations mentioned in the Hadiths which would've been fine if different narrations didn't claim different varieties that contradict each other. (I am not asking this disrespectfully, I have the utmost love and respect for my Prophet (SAW). I have only posted this to gain knowledge and have a better understanding of the issue. May my Lord forgive me for my sins and shortcomings.)