From Book IV of Master Dogen's Shobogenzo (Nishijima/Cross translation) pages 178-179 of the chapter Kei-Sanbo (Taking Refuge in the Three Treasures), last night I stumbled upon a passage in which it would appear that precepts are to be found in abundance:
...Typically, following the wrong teachings of non-Buddhism, [people adhere to] the ox precepts, the deer precepts, the rakssa precepts, the demon precepts, the mute's precepts, the deaf person's precepts, the dog precepts, the chicken precepts, or the pheasant precepts; or they coat the body with ash; or they make their long hair into forms; or they perform fire rituals for four months; or they take air for seven days; or they serve to various gods offerings of hundred thousand kotis of flowers; and all their desires by this means they [strive to] accomplish. There is no affirmation that such methods can become the cause of liberation...

In this little excerpt, a whole new view opens for me vis a vis this word precepts.
It would seem that everybody, everywhere lives by precepts. It would seem that if an anthropologist were assigned to follow each of us around, observing our behaviors and taking notes, they'd be able to discern Rules for our behaviors and those rules would be our 'precepts'.

So Buddhist precepts are a special category of precepts among precepts. As far as I know, Buddhist precepts are a way by which harmony in the sangha can be engendered, maintained, protected. I get the sense that they serve as a kind of Amy Vanderbuilt/Emily Post etiquette for many different people living together in close monastic setting under conditions which could at times have additional stressors (rainy seasons, little or no food, etc.)
How to preserve harmony? Precepts!--but not just any ol' precepts--Buddhist precepts!
No one says you're limited to only practicing Buddhist precepts while in the sangha or while interacting with other Buddhists--why you can practice Buddhist precepts wherever you find yourself and with whomever you happen to be with: they are a means by which circumstances can be approached in such a way that harmony is maintained, (or engendered if it is not present).

But it is very interesting to note from this excerpt of Shobogenzo that the precepts--even Buddhist precepts--are not a place of refuge.
And when we take them on, it is personal--I take them, and I promise to keep them well, I don't promise to enter into a competition where I strive to keep them better than someone else. These buddhist precepts are like my underwear: I might call them a personal 'moral foundation garment' and as such they aren't a subject for typical social conversation. Only I know how often I need to 'freshen' my precepts so that they function non-offensively--both to myself and to others in contact with me. Some people wear 'push up precepts' or 'fanny enhancer precepts' and it looks like they've got precept cleavage, or abundant buttocks: an illusion. To my way of thinking, Buddhist precepts aren't there to make me look more attractive--(that might be the function of another kind of precept somewhere in the inexhaustible list of ox, deer, chicken, mute person, etc...)-- I believe when Buddhist precepts are fully functioning they aren't noticeable at all: odorless, colorless, formless, I believe it would feel like wearing nothing at all.