Immigration Law Calls for a Fine

Immigration law spells out the penalties the government may impose upon those who enter the US at a time or place not designated by the US. 


Guess what the FIRST penalty listed is.


Did you guess a fine?



You'd be right.



So why jail them?



"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  . . . ."



https://www.law.cornell.edu/uscode/text/8/1325#