I am going to be downvoted to oblivion but sanctuary cities for what you are saying is like a monkey patch in code. It "works" for now but it's not a long-term viable solution. A person breaking the law and be fine to be a criminal to be in a country is already the wrong mindset. And these persons are only at step 1 in a life in the US. What happens when life will be tough later are they now magically going to stop all criminal solutions? Their solution to be in the US was already to break the law.
Thankfully there are already laws to protect people being persecuted, in danger, people needing asylum, etc... We need even better laws in these areas and improvements in witness protection laws for a part of your example. But again sanctuary cities "work" for now but it is not a long-term solution. Beyond attracting criminals, it also creates a weird lawful oxymoron at the opposite of the rule of the law. (And again, there are things like asylum, etc...)
Thankfully there are already laws to protect people being persecuted, in danger, people needing asylum, etc... We need even better laws in these areas and improvements in witness protection laws for a part of your example. But again sanctuary cities "work" for now but it is not a long-term solution. Beyond attracting criminals, it also creates a weird lawful oxymoron at the opposite of the rule of the law. (And again, there are things like asylum, etc...)