The taxa are definitely identified using iNat database according to the app itself. My guess is that Seek checks the USDA’s plant database (and/or other) for these labels after the taxa has been identified through the iNat database. Obviously the developers know, but I share this FYI in case it encourages the vote on this feature request:
Most of the plants I pull up on Seek are labeled Native or Introduced–approximately 160 out of 180 of my Seek observations get one or the other label in Seek.
I say approximately, because it sometimes takes 5 seconds or more for the label to appear on the app and sometimes I’ll return to an entry that doesn’t have a label but I happen to know is native, and it is labeled. Both the delay and occasional failure to match suggest to me there is a matching ID process with another database.
Of the ones that aren’t labeled native or introduced, I have found many are ambiguous or misidentified through my own photo comparison. Often they have Wikipedia entries describing ranges outside of the US. Some of the ones that are unlabeled have a look-alike/relative in the US that is identified by the app as native in a different photo of the plant I have taken in the same area. This is the basis of my suspicion that Seek .checks the USDA database–which goes down to the county level for many species–for these labels.
Interestingly, I notice common garden herbs (Lavender, Rosemary etc.) are not labeled Native or Introduced by the Seek app. (I also learned through Seek that the Venus Flytrap is threatened, endemic and native in North Carolina when I visited a botanic garden there last weekend!)
In order for it status labels be used elsewhere as I have suggested, without slowing the app, the data might have to be less dynamically connected/fetched. But I doubt it changes that frequently to matter. There definitely does NOT need to be an effort to label when that research has already been done for most species, at least in the US. (As I write this lack of similar databases globaly could be a constraint to more prominently using native plant labels in either app.)