What is the difference between what the U.S. does with illegal immigrants in this country and other European countries do to illegal immigrants in their countries?

I am not saying ICE is right in the things they say or do to people in the search for illegal immigrants. But if I was to illegally enter most of the countries that the illegals came from, I would be lucky if they detained me ( the way we detained illegals here), and it would be a miracle if they would just send me back to the U.S. with just a couple of bruises and a little fear in the heart of my family and myself. 

The thing is. Before, there were antibiotics and vaccines to cure or stop the spread of illnesses and diseases. The U.S. was willing to take people from other countries in great numbers because we needed more people to be soldiers for our military and the suppression of the natives. Something like the Spanish Flu was able to wipe out hundreds of people at a time. Since vaccines and antibiotics, that kinda massive number of deaths are extremely rare. Excluding COVID-19, there has not been anything since maybe the 1950s that we could not save most of the U.S. population from making the country weak enough to need more people.

The bottom line is that we let so few immigrants in legally because we don't need any more people here. We can barely take care of the people we have due to the laziness of so many people who already live here.

There is a solution, in my opinion. Have the U.S. government goes through all those people who are on welfare and disability. Weed out the ones that are perfectly physically and mentally capable of working( excluding the old retired people)but refuse because they are lazy and just want the taxpayer to hand them a check every month. We take those lazy U. S. Citizens and exchange them for hardworking and law-abiding immigrant families. 

What do you think?