just a quick FYI 

8 U.S. Code § 1325 - Improper entry by alien(a)
 Improper time or place; avoidance of examination or inspection; misrepresentation and concealment of facts 
Any alien who (1) enters or attempts to enter the United States at any time or place other than as designated by immigration officers, or (2) eludes examination or inspection by immigration officers, or (3) attempts to enter or obtains entry to the United States by a willfully false or misleading representation or the willful concealment of a material fact, shall, for the first commission of any such offense, be fined under title 18 or imprisoned not more than 6 months, or both, and, for a subsequent commission of any such offense, be fined under title 18, or imprisoned not more than 2 years, or both.

Civil penalties under this subsection are in addition to, and not in lieu of, any criminal or other civil penalties that may be imposed. 

you are correct in that things like taking a job or rape are added crimes