OK, this varies somewhat by jurisdiction, but my understanding is that the license that a user chooses for their observation record (as opposed to photos or other media) should apply only to copyrightable content within that record.
That would mean that if I write a detailed note or comment and set the license to CC-BY-NC, someone cannot reproduce any substantial part of that comment and use it for commercial gain. But I would be surprised if the core facts of my observation (location, date/time, etc.) surpass the threshold of originality required for copyright. So I can apply whatever license I want, but other people can use that data as they choose.
Then we come to identification data. It’s not clear to me what license supposedly applies to the identifications I give within iNat. Are these copyrightable? Absolutely there is skill involved, but not originality (it would be entirely wrong for me to dream up identifications). Jurisdictions that apply the “sweat of the brow” doctrine might be a lot more sympathetic to give the identifier rights over their identification. Of course, with iNat, the community ID is a product of the views of multiple identifiers, so it would be difficult for any one of them to claim proprietary rights.
So it seems that pretty much all of the data that feeds into iNat’s RG records of distribution for any species would appear not to be copyrightable, regardless of what default license a user chooses.
Of course, the license choice does affect how that data gets shared. For example, GBIF only syncs RG iNat observations that are licensed with CC-BY-NC or a more permissive license. So an EIA or developer working from GBIF won’t see observations with All Rights Reserved or CC-BY-SA licensing (for the observation, not the media).
Beyond that, there’s another layer of distance to consider. Let’s say @deedb8’s Local Environmental Records Centre, or another non-profit, produces a report that uses iNat data licensed as CC-BY-NC. Leaving aside some edges cases such as fundraising, we can be comfortable that the license terms have been respected in this process. Then a for-profit developer uses that report as part of its planning for a housing development. So long as the developer is not reproducing material from the report (or the underlying iNat contributions) there should be no issue in using the information it contains to inform their decisions. We would be in a bad situation if decisions on profit-making projects had to ignore data from any publication unless they licensed it.