The question is about deporting illegal immigrants specifically, i.e. people who are in a country in violated of its immigration laws.
I think the main benefit is the same as with any law: if you have a law with no consequences for the people who break it, you don’t really have a law. If we don’t have immigration laws, we have an open border and with an open border, we can’t regulate the rate at which people enter the country. This rate can easily exceed the amount that the country reasonably accommodate, which negative impact on housing, healthcare, welfare, transportation, civic cohesion, and education systems.
Immigration law is standard around the world, with deportation being the standard response to people who violate that law. The more interesting question here is how you think a modern country will function and continue serving the needs of its citizens when it stops enforcing its immigration laws.
> I think the main benefit is the same as with any law: if you have a law with no consequences for the people who break it, you don’t really have a law.
How do you feel about ICE raiding citizens homes without warrants? How about door to door raids?
If ICE cannot even follow the 4th and 5th amendments then they should be jailed themselves.
What if a law only has consequences for the people it's intended for?
Let's say you have a requirement that all TVs should be registered, so you can make sure every TV owner has a TV licence. You find an unregistered TV, but the owner has a TV licence. Does it make sense to confiscate the TV? What purpose would that serve?
Let's say you have a law that all people entering a country must be scrutinized to ensure no serial killers get in. You find a guy who hasn't been scrutinized, but he's not a serial killer. Does it make sense to confiscate the guy? What purpose would that serve?