We do, in terms of evidence. DS9 "The Circle" is unambiguous about that. Whether the native culture is capable of warp, subspace radio or perhaps telepathic contact with alien species across interstellar ranges, or possibly occupied by a starfaring culture, makes no difference in PD applicability.
And why should it?
PD is about noninterference. It has never been about noncontact: Kirk readily interacted with primitives, and only worried about the PD when dealing with cultures on the verge of starflight. Establishing a treaty or a contract isn't interference, apparently. Only very specific actions or inactions are.
We never, ever learned that the PD would exist out of fear of our heroes "contaminating" a primitive culture with advanced technology. It was always about contamination by ideas. Technology does not appear to be an explicit factor, and should not be considered when interpreting a noninterference situation in the episodes, either.
Obviously, a culture that is technologically incapable of interstellar contact will be more "pristine" than technologically more advanced ones. But only if those technologically advanced cultures decide not to make contact for their part. Bajor was in contact whether it wanted or not, so technology made no difference. OTOH, Bajor had long enjoyed an interstellar reputation of some sort, suggesting contact going back much farther than the Cardassian occupation.
All of their ships seem to be just for travel inside their own solar system.
What is a "Bajoran ship"?
The very first one we saw in DS9, a triangular ship with triangular warp nacelles in "Past Prologue", was coming from outside the star system. It was thereafter seen operated by the Bajoran military, but also by Cardassians, perhaps indicating it was Cardassian tech left behind at the withdrawal. Whatever the origin, Bajorans could and did go interstellar with it.
We had already seen a Bajoran ship incapable of warp in "Ensign Ro". But the plot called for that ship to be inherently warp-capable, with only its state of disrepair creating a nasty surprise for the Cardassians who were trying to frame the Bajorans for an interstellar crime. And we later saw that very ship type performing interstellar operations for the Bajorans, first in "A Man Alone".
Finally, a ship type introduced in "Move Along Home" was later seen hauling parties of other faraway cultures across interstellar distances on behalf of the Bajorans - and eventually operated by an actual Bajoran ("Indiscretion"), definitely far outside the Bajoran system. Its twin hexagonal arrays were of the same type as the single one on the "Ensign Ro" ship, suggesting common design origin; other cues pointed to Cardassia and its
Hideki class. And the design was seen in the hands of Cardassian satellite states, too. It's quite possible, then, that all of Bajor's current warp technology comes from Cardassia one way or another. It just doesn't make any difference.
Timo Saloniemi