Imprisonment until when? Because at some point you’d have to let them out, and then you’re back to square one. Crossing a border to seek a better life isn’t a crime worthy of lifetime imprisonment.

They won’t give them a path to citizenship because of xenophobia, plain and simple. Immigration is good for the economy, and there’s no such thing as “stealing jobs”, so it only comes down to wanting to maintain cultural (or ethnic) purity.