That process has existed since before America has, find probable cause someone is committing a crime, detain the suspect (you can get a warrant first but this is more common), get a warrant (can be done over the phone in a couple of minutes), put the cash away somewhere safe until the trial is over. If they are guilty of that crime and that cash was involved, great! If not you have to return it.

What we are talking about here is just taking the cash, sending you on your way and spending it, sidestepping your legal rights like access to a court provided attorney or a jury trial. It probably doesn't do much to prevent crime even, the fentanyl runners would much prefer you just take the cash they have on them and let them go.