Are we prisoners of sin

Yes one can. Current convention follows US traffic law since McMurdo station was the first establishment with enough vehicles to require some sort of organized road system. While I agree that sin is a religious concept, wrestling with your darker self appears to be a reality. We all have selfish desires which run counter to established moral or social requirements. If you are married, you still struggle with the infidelity even if you never give into it.
Can we say that we are a prisoner to this (moral/societal) lawbreaking side of ourselves? I don't think so, unless you consider the presence of the desire to be some kind of imprisonment.Paul's concept of sin follows Jesus' teaching that desiring to do wrong is also wrong, even if you don't follow through in your actions.
If this is accepted by the religious, then their internal desires make them prisoners to sin.While we all struggle with our selfish tendencies, our concept of it's incarcerating capability depends entirely on our theological outlook.