On this kind of devices the security chain of trust needs to take into consideration the same kind of users that fill their Internet Explorer with random toolbars from website popups.
Not the user with a CS degree that knows what they are doing.
"Of all tyrannies, a tyranny sincerely exercised for the good of its victims may be the most oppressive." - C.S. Lewis
Freedom to do what you want with the device you purchased is a right that is not to be infringed upon, especially not for the reason "the users might hurt themselves".
Setting up a technically nontrivial flow to unlock the bootloader (e.g. connect the device to a machine with an SSH client, approve SSH connection request with scary message, SSH to the phone, execute a shell script that tells you that you shouldn't unlock this unless you know what you're doing, and after confirmation the script unlocks the bootloader) is more than enough of a deterrent for the vast majority of non-technical users.
The remainder are acceptable casualties - people who refuse to read warning labels are going to have other bad things happen to them anyway (drinking poisons, injuring themselves while working with power-tools) as a result of their foolishness, and the solution to that is not to take away the power-tools from the whole population, but to train them to read and follow warning labels in the first place.
Those technically skilled users who want to unlock their bootloaders (and, you know, do what they want with the devices they paid for) should not have to pay for the stupidity of a small minority of foolish people who refuse to read warning messages.
As it is a right for a manufactures to sell their devices configured as whatever they feel like.
The consumer has the right to buy from companies that sell products that actually fit their purposes, like I don't know, a computer, instead of trying to replace the firmware in a toaster.
As a society we have already decided that manufacturers can't just configure the devices they sell however they feel like. One of the most obvious restrictions is on how they configure any radios. fouric is merely arguing that there should be another, and you're not responding to their points.
As such, your comments in this discussion, and this one in particular, do not appear to be in good faith.
Hence why radios are kind of locked down to makers that could make use of illegal radio frequencies, some of which could even be damaging to human health.
My faith is that not everything with a CPU has to be open to install Linux on it.
Those kinds of users are unlikely to replace the root of trust, simply due to the process being onerous.
And even if everyone were to install malware. There are other ways to secure banking. E.g. by providing an external token with a display. This is how hardware crypto wallets and some PIN generators for in-browser banking work. Or they could ask the owner to upload the attestation pubkey to their website, then the bank could still check if it's really their app that's running (as confirmed by the boot trust chain). I'm not sure how fingerprint scanners are tied into secure boot, maybe they could be used to verify user intent too.
Except the app is remote-controlled by a malicious “display driver” that waits for the user to do all this authentication set-up, transfers the money away, “are you sure”s it, then prevents the user from seeing any of the on-phone scam warnings until it's too late to reverse the transaction.
Not the user with a CS degree that knows what they are doing.