[knollimar]

I thought I had this line, but I imagined if my credit card had writable program memory, I'd be fine with a third party preventing me from using it for its intended purpose if it wasn't trusted there. There must be some purpose for my own good for preventing me from writing to my own program memory, and I should be able to void this purpose if I deem it worth it.

Likewise, I'd be fine with banking apps on phones requiring some level of trust, but it shouldn't affect how the rest of my phone works so drastically.

[kragen]

Why would your credit card need to act against your interests? The only thing it should be doing is signing transactions to signal that you approve. The credit card company has their own computers that can be consulted to ask them if they approve a transaction. They don't need one in your pocket. They can rent a rack in a data center. It's not that expensive.

Similarly, the banking app on your phone should be representing your interests, 100%. It may need to keep secrets, such as a private transaction signing key, from your bank or from your boyfriend, but not from you. And it definitely should not be collecting information on your phone against your will or without your knowledge. But that is currently common practice.