That's the problem, the federal government simply does not have the resources to prosecute all the alien smugglers. There are thousands arrested each week at ports of entry, BP check points and ICE interior enforcement operations.
The federal court system simply can't handle the load so generally the only ones who get prosecuted are cases that involve aliens getting injured in the smuggling operation. Like when they open an 18 wheeler and find a bunch of dead aliens.
Since prosecution is not possible DHS simply voluntarily returns the illegal aliens, deports the smuggler if they are illegal aliens or immigrants and seizes the vehicle (generally a POS) for later auction if it is road worthy.
Then the smuggling organization buys back the vehicle at auction and the entire process starts over again.
They don’t have to get them all just get the biggest ones first and hammer them hard. Also take down any government people that are on the take, get them especially hard.
The ‘Word’ will get out.
Use the procedes to go after the rest.