IIRC, the declaration form is circulated before landing.
yes the form is circulated but it must be given to a customs officer where you are questioned verbally..some airports now have done away with the form and have an automated kiosk where they check your passport take your picture and you answer the declaration questions then proceed to a customs inspector with a printed out copy of it. apparently he was arrested without a warrant...very unusual imo. coincidrnce that he was given 10k in cash? i think not.
https://www.cbp.gov/travel/us-citizens/apc