Two people go to their local supermarket and fill up their carts with goods.
The first goes into the self-checkout line, scans one low price item and pays for it, and when the clerks aren't watching, runs out the door with hundreds of dollars of merchandise that he never paid for. When the store discovers that this merchandise is missing, they call him and politely ask him to return the items that he didn't pay for, but he refuses to do so. Eventually they have to get a warrant to go to his house to seize the stolen stuff. When they do that, he has a complete meltdown and screams that they are taking merchandise that belongs to him (even though he never paid for it), because he says so.
The second shopper takes his cart to the self-checkout line, scans all the merchandise (or so he believes), leaves the store and goes home with what he believes to be legally purchased food. Later, when he's looking over his receipt for the items he bought, he notices that he was charged for only three boxes of macaroni, even though he has four boxes of macaroni in his possession. He realizes that he must have either forgotten to scan one of the boxes, or the scanner malfunctioned and didn't read the barcode. In any event, he knows he has a box of macaroni that he did not pay for. So he does the responsible thing, goes to the store with the box of macaroni and returns it, acknowledging that he must have forgotten to scan it when he was checking out his purchase.
It should be pretty evident to anyone which person represents Trump and which person represents Biden in this little story.