Because it was amnesty. There were no fines, incarceration or probationary supervision associated with the 1986 Act, no tax enforcement associated with the 1986 Act and no permanent criminal record associated with the 1986 Act.
That's what amnesty is: no criminal penalties, no criminal record. Complete forgiveness.
What they did back then is no different than what you and Bush want done today.
The President's failed plan and my proposal are different in a number of respects.
The President's plan did not call for a DNA database, did not call for deportation on all post-immigration criminal charges, did not call for full back taxes plus penalties, did not call for fines, did not call for probation, did not call for a permanent criminal record, and did not condition naturalization on payment of fines and back taxes.
You would do well to actually learn about these matters before equating things that are not equal or even very much alike.
The 1986 Act was amnesty. My proposal - which calls for criminal and civil penalties and a permanent criminal record - cannot be called amnesty by any honest person who has learned how to read.