Why did Allah not regulate the religion for us, despite His commitment to preserve it, especially with the existence of outwardly contradictory hadiths, which leads to scholars differing on whether to abrogate one of them or to reconcile between them?

Disagreement on subsidiary issues indicates the breadth and flexibility of Islamic legislation, and the differences among the mujtahid imams are a vast mercy. Allah did not establish definitive proofs for all Sharia (definition) rulings; rather, He made them probabilistic intentionally, to provide latitude for those who are accountable. This disagreement does not lead to discord, unlike the disagreements of people of whims. Moreover, the varying clarity and indication of evidence is a test to distinguish sincere believers. It is obligatory to refer to Allah and His Messenger when disputing, as Allah the Almighty said: "O you who have believed, obey Allah and obey the Messenger and those in authority among you. And if you disagree over anything, refer it to Allah and the Messenger."