Brawlers and unchained monks don't get any special abilities that grant them attack roll bonuses. Antipaladins and paladins don't gain bonuses outside of smite, which has a limited number of uses per day and doesn't help if you're not fighting opponents of the character's opposed alignment. Cavaliers also don't get bonuses on attack rolls unless they belong to a specific order (like the order of the cockatrice) that grants them one. Those bonuses are usually situation (i.e. be the only person threatening your opponent) or tied to the challenge class feature or some other limited uses per day ability.
So no, the vigilante not getting attack boosts is not unusual. Fighters, barbarian, bloodragers, and slayers are the only full BAB classes that can get those attack bonuses with any amount of assurance.
Paladins and Rangers get spells that increase their BAB and monks and brawlers get extra attacks.