Much of American immigration law is arguably unjust. Did you know that if you are taken into custody for an immigration violation, you may not be entitled to any sort of hearing for as long as 6 months? Did you know that there have been many cases involving illegal abuses of people in immigration detention? Did you know that American citizens have been wrongly reported? Also, the process of determining who is deportable is nowhere near as simple as you suggest. Not everyone who comes here illegally is deportable even under a narrow reading of the law.
It is precisely your sort of poorly-informed complacency that enables human-rights abuses to occur in the first place. Of course, maybe I've read you wrong and you're OK with some people having their rights violated, in which case further conversation is pointless.