Why did Samson | שִׁמְשׁוֹן Shimshon not observe the Vow of Naziriteship?
Nazir 4b [3]
A nazirite like Samson is permitted to become impure from a corpse ab initio, as we find with Samson that he became impure. Rabbi Shimon says: One who says he will be a nazirite like Samson has not said anything, since we do not find with Samson that an utterance of a vow of naziriteship left his mouth. Samson never took a vow to be a nazirite. He received his status from the angel’s instructions to his mother (see Judges 13:5). Consequently, Rabbi Shimon holds that one who vows to be a nazirite like Samson is not considered to have taken a nazirite vow.
Nazir 4b [17] states
וְשִׁמְשׁוֹן לָאו נָזִיר הֲוָה וְהָכְתִיב כִּי נְזִיר אֱלֹהִים יִהְיֶה הַנַּעַר מִן הַבֶּטֶן הָתָם מַלְאָךְ הוּא דְּקָאָמַר " The Gemara challenges the assumption that Samson’s naziriteship was not accepted through a vow: And was Samson not a nazirite whose naziriteship was accepted by a vow? Isn’t it written: “For the child shall be a nazirite of God from the womb” (Judges 13:5)? The Gemara answers: There it was the angel who spoke. Samson’s nazirite status did not stem from a vow uttered by a human being. "
Did Samon | שִׁמְשׁוֹן Shimshon become impure from battle at לֶ֔חִי Lechi?
"The Gemara asks: And from where do we derive that Samson became impure from corpses? If we say it is from the fact that it is written: “And Samson said: With the jawbone of an ass, I smote a thousand men” (Judges 15:16), perhaps he thrust the jawbone at them but did not touch them, and he remained pure." - Nazir 4b [18] : https://www.sefaria.org/Nazir.4b.18?with=Commentary&lang=bi