Why did Al-Bukhari not narrate from Al-Shafi'i and Abu Hanifa?

First: Al-Bukhari did not narrate directly from Abu Hanifa and Al-Shafi'i for a clear reason: he did not live long enough to meet either of them. Al-Bukhari was born in 194 AH, Abu Hanifa died in 150 AH, and Al-Shafi'i died in 204 AH, at which time Al-Bukhari was only ten years old.

Second: Al-Bukhari did not include any of their hadith: 1. Regarding Abu Hanifa: Al-Bukhari was very strict about chains of transmission (isnad), and he saw that Abu Hanifa's focus was more on jurisprudence (fiqh) than on hadith, which meant he did not reach the level of memorization required for "Al-Jami' Al-Sahih." This is why Al-Bukhari said in his biography: "They were silent about him, his opinion, and his hadith." 2. Regarding Al-Shafi'i: The reason was not that Al-Bukhari was unconvinced by his memorization or trustworthiness. Rather, Al-Bukhari sought older, higher-ranking shaykhs to elevate his isnad and draw closer to the Prophet, peace be upon him, with the fewest number of narrators. He had shaykhs who narrated directly from Al-Shafi'i's shaykhs, without needing to descend in the isnad. Thus, relying on Al-Shafi'i was not abandoned due to any weakness in him, but rather because it was sufficient to use something higher in the isnad.