A useful way to hold this word is the laurel crown at the end of a course of study. Somebody has worked for years; now there is a moment where the work is closed off and marked. All three uses sit on that moment, and they differ only in what is handed over at it — a set of exam results, a degree, or a speech and a quiet evening before the certificates arrive. The word is long and formal because the moment it names is a formal one.
From the word’s history
The supplied source says the word came into English in 1625 from French baccalauréat, from Medieval Latin baccalaureus, itself an altered spelling of baccalarius (a young man aspiring to knighthood, an apprentice) reshaped to look like bacca lauri, laurel berry, the ancient sign of victory. That deliberate reshaping is where the crown picture comes from, and the same root gives English bachelor.
packet 附的來源說這個字 1625 年進入英文，來自法文 baccalauréat，再往前是中世紀拉丁文 baccalaureus。那個拼法其實是把 baccalarius（見習的年輕人）改寫成看起來像 bacca lauri，也就是古代象徵勝利的月桂果。冠的畫面就是從這次刻意的改寫來的，而同一條線也長出了英文的 bachelor。
Wiktionary, "baccalaureate"
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