Every Labor Day weekend we book our winter Caribbean vacation flight. Each year it’s the same routine; sitting at the computer, finding earliest flight down and latest back, entering credit card and passport information, printing out docs.
This year the passport information step was glaringly absent. Any idea why that would be? Do any airlines save and reuse the data? I’m nervous now. Anyone else have this happen? 
American Airlines, if that’s relevant.
Is it saved in a frequent flyer profile? Mine is with Virgin Atlantic.
As far as I know, I do not have one.
I’m hoping that’s it.
It could be that in an earlier booking the info was saved (though you would have had to click to do so). I take it the travel is Caribbean/International, i.e. other than PR/USVI?
I was not prompted to enter passport info for my upcoming international flight on Delta. Booking was made near end of July, IIRC, for travel this upcoming weekend.
I was prompted for such info for my trip back in April on American.
No idea if there has been a real change since then or what.
Yes, Saint Martin/Sint Maarten requires a passport.
When I made reservations to go to BVI several months ago, I didn’t even have a passport at the time. There was no problem with the reservation - they just made me show them the passport when I checked in. I think the airline only cares about your passport because they don’t want to be stuck having to take you back if you get refused entry to the country - they don’t actually do anything to give your passport info to the destination country.
This will be my eleventh consecutive vacation in St Martin. Every time (until yesterday) I bought my plane tickets online and had to input my passport info.
Confirmation email looks fine. 
Sure, but what I’m saying is that there was no legal reason for you to be required to do so - it was solely the airline’s requirement. So they may have stopped doing it.
I’m trying to remember but I don’t think you need it for booking but you’ll need it if you check-in online (24 hours before the flight). I am looking at the flight I booked for Germany in December and I think all I needed was my frequent flyer number to book it.
Guess I’m just gun-shy about air travel.
A few years ago my business manager booked a round-trip flight and spelled my middle name “Steven” instead of the correct “Stephen”. I never noticed, but TSA did and gave me a tough time on my return flight.
A year later she booked a return flight for 6 am instead of 6 pm. I noticed the night before departure. We couldn’t take the am flight without making my entire trip meaningless and there were no flights in the pm. We flew standby and paid close to $900 extra (Four-something for me, four-something for GF).