I've only ever experienced preclearance before in Canada, in which one of 2 things happened:
1) If I was originating, the airline tagged my bag, I went through USCBP, then deposited my checked bag and went through CATSA
2) If I was connecting, I went through USCBP where an image of my bag was brought up

Last week, as an orginating passenger in NAS, I checked in normally with the airline and they collected my bag, went through Bahamian security, then went through USCBP with no bag or picture thereof (at least that I could see). I know that historically the US is adamant about having access to all items going through customs (which is why you can never connect airside on an int'l itinerary in the US), so why is this setup allowed?

As an aside, they have the most ridiculous process at oversize dropoff. For each item, they had to scan the bag tag, scan a barcode for the item type, then handcopy some information from my boarding pass and the digital display onto a paper log, then scan a barcode indicating "complete" before putting the bag into the scanner.

The preclearance flow for originating flights in Canada changed some years back, and now you drop off your bags immediately after check-in, then go through CATSA and finally USCBP. CBP officers have pictures of your bags available during processing similar to your connection experience, and sometimes they've asked me how many checked bags I have and to confirm a bag in the picture is mine. At that point they could pull it for further inspection before it's loaded onto a plane. It sounds like that's how it's being handled in NAS. Did you actually see the officer's screen with no pictures of bags on it?