They are detained after being caught, during the process they are given a court date for immigration court. With the amount of illegal immigrants the immigration court is back logged so their court date isn’t anytime in the near future, some might even be in a year or two.

Once they receive their court date they are either released and expected to appear to that court date. They are being bused to sanctuary cities where they are dropped off.

The point is they are released and expected to appear to their court date, which doesn’t happen.