Depends on the Bank at the moment. I changed my phone this year so needed to visit KrungSri and Bangkok Bank to get my Banking Apps working again. I updated my Bangkok Bank Passport with a signature. KrungSri wanted a photo. Took 5 minites so not a big deal.
Also, never been charged a fee by the vendor or PromptPay. The only place I use cash for the last couple of years is at the 7-11 and I understand they are starting to accept PromptPay at some locations. Almost all restaurants, food carts, market vendors, food delivery guys have a QR code.