Alright, let's measure all known city-states and city-state-like regions:
Ul'dah, Gridania and Limsa Lominsa: Pretty high fantasy, no overt technological themes.
Ishgard: Likewise, just with more dragons, the most they have is a fairly recent engineering group.
Ala Mhigo: Pretty middle eastern, actually ties with Ul'dah for this, there is a significant technological presence but that's not for Ala Mhigo's culture in itself, it's because of Garlean occupation.
Kugane, Doma: Fantasy Japan to a tee.
All of Novrandt: Different flavors of what we already had in the Source, it's the point really, less technology around but also in large part due to most of their planet, including their version of Garlemald and Sharlayan, being nuked.
Radz-at-Han: This is just India and also there is a dragon around.
Garlemald and Sharlayan: By far the two most technologically advanced nations, but also it makes perfect sense for that to be the case, Sharlayans are hoarders of knowlege, and Garlemald's entire thing is their inability to wield aether the same way as every other race causing them to push for technology.
Tuliyollal: It's Mesoamerica, they actually have even less technology than most other city-estates, as their most pronounced sources of technology, their dirigibles and locomotives, are not only very recent, they are entirely imports.
Alexandria: The most technologically advanced nation in the Source and the only one that is fully sci-fi, and they are literally alien to the entire Shard, being brought from the Ninth due to Dimensional Fusion, we can also give them benefit of doubt as thanks to the Alexandria dungeon we know that in the past they were very high fantasy as well, and the catastrophes of their Shard is what caused them to push for technological advancement, I could also point out that while they are aesthetically and thematically sci-fi, they are actually magitek in their near entirety, Regulators work by manipulating souls, Electrope is just a catalyst to manipulate aether, even all their technology ties back to magic.
Bonus, Bestways Burrows: Not a city-estate per-se, but the original intent of it as a colony for humanity should make it count enough, and they are very much a different flavor of sci-fi while also leaning into magitek like the Alexandrians, even featuring multiple multi-aspected crystals all over the place, which, in my opinion, makes the magical aspect of their technology more pronounced.
TL;DR: I feel saying that "sci-fi is the norm and the 3 starter cities are backwards" feels disingenuous, even now, technology is rare and sparse and the average citizen sparsely, if ever, see even a single robot, we see a lot of it because we are very special, the most talented and powerful adventurer in the planet, the rare and unusual is the norm for us, and we shouldn't see the things the WoL deals with as "this is what the world is" and more "this is what exists in the world".