Privacy

This is why everyone should go into their phone settings and enable the lockdown mode option if it's avaialbe. When I get pulled over I hold the power button and choose lockdown mode and then the only thing that will unlock the phone is my password. But my camera still works.

If your phone doesn't have the option, just restart your phone. There's a reason phones require the password and not biometrics on startup.

Things like passwords, access to the interior of your home or vehicle, access to your business files, and things like that are not your identity and normally require a judge to sign a warrant

This is exactly it. If I get arrested and they confiscate my house keys as part of entering jail, they don't have automatic implicit permission to search my house.

My house key identifies me almost as well as my license. Seems like if they can use my thumb to unlock and enter my phone they could use my house key to unlock and enter my house.

There are two related but distinct issues, and I hope to keep them separate otherwise the conversation goes in circles:

1 - Can police under the circumstances look at the contents of the phone at all? This is to say, if the phone is completely unlocked, can they look through it?

2 - If the police are allowed to look at the contents, but the phone is locked, in what ways can the police unlock it?

Subject 1: This is by far the more important question, and the one that seems to get ignored in discussions of phone searches like this. I would argue that under most circumstances there is no probable cause to search a phone- the phone can not contain drugs or weapons or other contraband, so to me this is the larger hurdle for police. Police should have to justify what illegal thing they think is on the phone that gives them probable cause, and I don't think that pictures of illegal things are the same as the illegal things themselves. Lawyers would have to hash this out, because I do notice the suspect here was on parole so perhaps there is a clause of parole for this or something. But this is the bigger, much bigger issue- can police even look at the contents? There is an argument from the pro-search side that constants of an unlocked phone are in plain view, and so that right there is a big nexus for the issue.

Subject 2: If we assume yes, only then does subject 2 become an issue. How much can police compel? Well, they can't compel speech. A passcode would count as protected speech, so they can't compel that. Biometrics however, from what I have seen of court reasoning, tend to be viewed as something a person has rather than something they know. This would be analogue to a locked container with a combination lock compared to a key. The police can not compel the combo, but if they find they key in your pocket they can take it and use it.

If you are up in arms about privacy, my view is not to fall into the trap of focusing on 2 and the finer mechanics of where the line for what kinds of ways to lock a phone are, and focus on subject 1. Reduce the circumstances in which searching a phone is acceptable, even if the phone is unlocked to begin with.