Simply the truism that politicians tend to focus on issues that have reached a crisis point: in 2001 the problem uppermost on people's minds was terrorism, not illegal immigration.
I'll take that as "Yes." Thanks.
There's simply no reason the border and immigration enforcement should not have occurred aside from lack of desire, which is disheartening particularly after 9/11. This lax enforcement includes those who overstayed or fraudulently obtained visas, not simply border crossers from the south.
That a Republican president would willfully push for unnecessary immigration reform (as opposed to simple enforcement of existing law) makes it even worse, particularly when one considers the astonishing number of illegal foreign nationals who will be granted amnesty, let alone the social and economic consequences of such policy.