There is a simple reason for that: Both Donald Trump and Joe Biden believe in America's system of immigration controls. Their only difference between them is over the enforcement measures that come with that system.
Alas, needless to say, that is also the position of the mainstream media. That's why there has been no pushback on immigration in the presidential race. Don't expect any, especially in the remaining presidential debates.
There is a simple reason for America's decades-long crisis in immigration. America's system of immigration controls is based on the socialist principle of central planning. As everyone in socialist countries will attest, central planning produces crises. A good term for such crises is the one that Ludwig von Mises applied to the results of central planning: "planned chaos." What better term to describe America's decades-long, ongoing, never-ending immigration crisis?
Trump and his Republican cohorts love to proclaim their support of "free enterprise" and "free markets." Yet, free enterprise and free markets mean enterprise and markets that are free of government control and interference. A system of immigration controls is the opposite of free enterprise and free markets.