Well I always thought that certain races if they wanted too would keep a small home fleet. Like a local militia
Starfleet would cover Federal level defence but other races could help out by having a small fleet of there own, though it would have no jurisdiction elsewhere.
Also we see Human civilians operating starships in Starfleet independent exploration. Normally Oberth classes or in the case of the Hansen family the Raven. So makes sense other Federation members would do the same