The Torah's commandment regarding kindness to strangers referred to the
ger or sojourner - one who was willing to abide by the "one law for the native born and for the 'stranger' who dwells among you" standard. It was not applicable to foreigners who chose to remain aloof. Before Ruth entered Israel with Naomi she famously declared "your people are mine, you God is mine". She adopted her new culture and turned her back on Moab. I doubt that very many of our current "illegals" are emulating the attitude of Ruth, the Israelite.
Rather, most of our illegals have the attitude of Amalekites, Edomites and Ismaelites. They want to displace the extant culture with their own.