The Easycard Wallet which could previously tell you your card balance and display your receipts has had a revamp. You can now use the app to make purchases instead of fishing out your Easycard. Unfortunately, you won’t be able to register for the pay function without a Taiwanese ID until the end of May according to a Customer Service representative (ARCs do not meet the required format and no alternative is given for foreign residents to sign up.)
A customer service rep sent the following message, saying that foreign residents will be able to register for the app starting at the end of May. They’re phrasing it like it was a planned rollout as opposed to just bad programming and lack of forethought, but hey… it’s something:
Thanks to Slava for the tip!
June 3 Update: The app was updated on May 29 to allow foreign ARC holders to sign up as the company promised, more details here.