Americans can help stop that by refusing to fly on any airline or ride on any bus that transports illegals. We need to speak with our wallets more. If companies are not doing what you consider good for America, then let them know that you are spending your money with companies that do support a healthy America.
One example I cancelled my Geico MC insurance 2yrs ago. When they asked why, I told them they do not support our 2nd amendment so I will not support them with my money.