Why was the traveler not mentioned among those for whom Friday Prayer is waived in the Hadith: "Friday is a duty incumbent upon every Muslim except four"?

Friday prayer is obligatory for every Muslim in congregation, except for four: a slave, a woman, a child, or a sick person, as stated in the حديث طارق بن شهاب (Hadith (definition) of Tariq bin Shihab). To these are added the traveler, due to other hadiths that exempt them, and the bedouins. The mention of a specific number in some hadiths does not imply exclusivity, but rather may be for ease, as Islamic rulings are derived from the totality of hadiths.