"Waste of resources" is relative, since there are people getting good and paid for participating in this operation, including local governments that detain immigrants in exchange for large sums of money from the Trump government; private prison corporations that run the facilities to detain them; and the various companies that provide services to facilitate the apprehension and detention, all of which creates a clear incentive to detain as many people as possible.
But even setting this aside, red hats don't want due process for immigrants because they can't enjoy witnessing any cruelty during court proceedings the way they can watching video of raids.