Legal processes which have requests from nearly 10 years ago that havent been opened yet
Now i am not trying to say its right to illegally cross the border. But the US underpays and has way way too little immigration judges. The wall wont work. But paying for more imigration judges will solve the issue at least to an extent.
Less people would cross the border illegally if they didnt have to wait years for their application to maybe be looked at.
And since theese people are often running away from shitty conditions, wars, gangs etc. They cant just wait 5 years so that they will be told "no".
Ofc if crossing the border is a better alternative to starvation or death or sth they will do it.