Live in Wayfarer 3.1 is a new set of acceptance criteria! Please browse the information in this category with caution as it is in reference to the previous review guidelines. To learn more about the new criteria, see here: https://niantic.helpshift.com/a/wayfarer/
Well that's where you're getting it wrong. The guidance is that street art is acceptable, not "all street art is accepted".
Once they have established something is acceptable, reviewers must still apply all the normal checks: is it K12; is the photo blurry; is it on private residential property, is it temporary, does it have historical or cultural significance, etc.
If something is likely to be painted over because it's vandalism, then it's temporary and should be rejected. If "your kids could do better" as someone mentioned above, then it should get an appropriately low number of stars for historical or cultural significance.
I would be careful using an extreme example like the Eiffel Tower (which has become one of the most recognizable landmarks in the world) to justify approving graffiti on a wall.
The subjective nature of art is exactly why we have a rating system with multiple reviewers. I'd say that to the majority, it's pretty clear what's culturally relevant art and what's not. And for cases that appear to fall into the latter category, it's up to the submitter to make their case in the supporting statement.
Here's an example: in my town, we have an alleyway that has been covered (with city approval) from end to end in graffiti murals. Some of them are poor quality, others require a stunning level of artistic talent. Many of the individual artworks were approved. Some of the lower quality ones (even though sanctioned by the city and expected to be visible for at least a decade) were rejected.
But a few blocks away, at an abandoned train station, we have illegal graffiti that is, nonetheless, very skillfully done. It's never been approved in Wayfarer, and I know someone submitted it. From the submitter's standpoint, it's very difficult to justify that one even with a good supporting statement and photo.