You suggest they're removed.....do they get a hearing first?  Are they ROR while awaiting said hearing?  Given enough claimants we certainly wouldn't be able to detain them all waiting for hearings which is the problem.  Not yet perhaps but the numbers are going to go up, likely to the point that all will be ROR.

Given that the law states they must be returned how many do you think will actually show up for their hearings and how many will disappear to one of the "sanctuary cities"?

Stop them at the border, let the US take them back then and there.