Which was surprising to learn since it did get a DVD release in 2007 with extras that included a commentary track from director Lewis Teague and star Robert Forster. Alas, that DVD is now out of print, and the bootleg copy I bought off of eBay (I know! I know!) was a pan and scan version. The horror!
It's not streaming on any service either, so I resorted to watching a version that is available on YouTube which is at least in the correct aspect ratio, and during brightly lit scenes, looks pretty good. It's too bad roughly half of the movie takes place in dark sewers!
On the surface, Alligator seems like your run of the mill Jaws ripoff, this time one inspired by the urban legend that pet baby alligators that were flushed down the toilet when they lost their cuteness eventually grew up in the sewers to be man-eating monsters. (Turns out, some of that is not entirely legend, and this awesome NYT article delves into the truth.)
But this one was written by John Sayles, who also wrote another above par Jaws ripoff, 1978's Piranha. And similar to that one, what sets this one apart are the performances (Robert Forster is great); a good sense of humor; and some moments that do nothing to further the plot, but are just fun to watch. (My favorite is a scene involving an old guy in a tuxedo talking about how to grill meat.)
If you can get your hands on the DVD release, that's how to see this, otherwise the only streaming option is the above linked-to YouTube option.