And, of course, some real banks:
The prize for having the most “interesting” reaction to seeing a TARC definitely goes to HSBC, more specifically their Linkou branch:
It all started out quite fine. I walked into the branch, showed the guard my HSBC-branded ATM card (to calm them down by showing that I am already a customer and not coming to open an account) and my TARC and just told him that it’s a new one. He happily handed me a number which was called a couple of minutes later.
The issues started when - after checking the TARC briefly - the employee asked me to see my passport. I happily handed over my TW passport. And that’s when the employee became visibly confused.
The confusion became stronger and roughly the following conversation resulted:
- “Why you want to do this???”
- “???”
- “Why you want to update?”
- “Uhh, I have to, I guess…?”
- “If you update, you won’t be able to use online banking anymore. And we need to cancel your credit card”
- “?!?!??!??!”
I don’t remember the exact sequence of events that followed, but a couple of minutes later, I was holding my TW passport in front of the bank employee who just kept exclaiming rather loudly: “不是台灣人! 不是台灣人! 不是台灣人! …”.
At this point, I thought I had to leave the branch and send a formal complaint. However, the employee regained her composure and told me to wait a bit. She made another phone call. After some minutes (which felt like an eternity), her mood had changed considerably, and she finally handed me a form to fill out for changing my nationality on record to TW. She finally admitted, too, that I am in fact a Taiwanese national, they wouldn’t need to cancel my online banking or credit card; the TARC just looked to similar to an ARC to her. And she only hesitated briefly when I filled out that I am only a tax resident of Taiwan and no other country 
I still don’t know what her first assumption was about my status - she truly seemed to believe that it was some kind of non-resident status, so that would explain why she initially thought they needed to restrict my account.
Compared to that, the process at E.SUN and Cathay was rather smooth (except for very long waiting times compared to HSBC…).
Maybe that was because of those two banks, neither asked me to see my passport. At this point, I’m about 80% sure that they both never noticed that they were in fact holding a TARC and not an ARC, and so they just went through the “new-ARC”-SOP without noticing the difference. I didn’t have to fill out any form at both. After my experience with HSBC, though, I didn’t really care… 