Well we all have our own experiences i guess. There is a joke 3 country concept in Taiwan amongst many people. the 3 nations in taiwan (perhaps one could compare to UK for a light hearted comparison). There is Dragon country, the mainland and orchid island.
but in all seriousness there are distinct cultures that are very recognizable, though not always a genetic difference where race (dare i say, subspecies…) are differentiable. The SW of taiwan is just more extreme everything that comes out of the west. and it makes sense that undeveloped taidong back in the day would have a different kind of person living here in comparison to the big city life. then over time morals, ideals, works, industry etc follows. i see a huge difference in the general concept of longetivy and respect between Taidong and Pingdong. it is really quite large. though i guess we are mostly talking about Mingnanren not so much aboriginals.
for aboriginals, at least the lines from the mountains, there are numerous similarities but also huge differences. often simply due to financial situations (for example the Paiwan in Sandimen/Majia area are historically financially far more well off than across the Dawushan ridge in Taidong…trading logistics and inner governance).
I think anyone that has lived in Pingtung as a welcomed member of the community (basically merging into a local family) can see there are some pretty serious issues there. these exist in many places, scattered around, but rural Tainan south is a whole different ballgame than the random villages of sadness scattered around like in any country.
Taidong is surprisingly fresh and open minded, in my opinion, compared to much of the island, even the north. It is still very much countryside and you get pockets of depressed locales, but overall it is worlds apart from places like pingtung.
Though as a tourist, passer by or have a weekend house, these subtleties wont be observed. within these places, as an example, Hakka towns and villages are notorious for being close knit. you dont find out much about them until you live with/next to them for a while and gain their trust. on the flip side many southern aboriginal areas are quite open and slightly easier to gain trust.
Taidong in my opinion is one of the best places in Taiwan. Hualien i find the people more educated and prefer it there myself. But it is way more expensive and quite wet. Issue with Taidong is you should have your own business and have a decent line up of income, cause it isnt always easy for foreigners to live financially comfortable lifestyles as if in the west.