I don’t get it. Where are these searches performed? At the airport? If so, how does civil forfeiture come into it? They keep my luggage? I always thought that typically these loathsome forfeiture rules come into play if you posses stuff within x feet of your home or car. And if they use a database to determine that my perfectly legal travel is “suspicious” (i.e. to profile me) how the heck do they get a judge to buy into the fact that I fly a lot as probable cause of a crime in order to get a warrant to search my HOME? Makes no sense to me.
Searches may typically be performed at the airport, or at roadside checkpoints, or as a result of a "routine traffic stop".
Any sizable amount of cash may be seized by the police simply on their declaration. They may take other valuables as well, such as gold, jewelry, pre-paid gift cards - or your vehicle. They do not have to arrest or charge you with anything.
The seized assets are usually given to the police department.
If you are selected for this party, you must sue the Government and prove that the seized assets were obtained through lawful activities in order to get them back. That will generally cost more than the value of the assets - and you won't get reimbursed for your legal fees, even if you win.
You may wonder what happened to your 4th amendment protection against "unreasonable search and seizure". The answer is that the Government simply ignores all of those inconvenient constitutional limitations.