R. Hartzell mentions:
…your bank accounts, bank CDs, credit cards, and private life insurance all use your ARC number, however I suspect that this is untrue. Commonly, such accounts use the foreigner’s passport number. The post office uses the TAX ID number [19600101AA etc.], while the phone co. uses the passport number.
Even if plans to give permanent residents a standard ID number go through numbers like AA1234567 with two letters at the front will be little help in allowing us to participate in various automated services that assume a standard ROC ID #.
In the USA, non citizens can not only get standard looking social security numbers, but they can also become citizens without the supreme sacrifice of ones original citizenship as in Taiwan.