Right-side doors are for catering, not pax. I think there would have been a webbing barrier across each door while they’re waiting for the catering trucks to arrive. Looks like it was a nice sunny day, so they may well be open to afford ventilation too.

The VC.10s just had a single webbing strap across the catering doors at around waist height which essentially warned you that it was an open door-but it would have been relatively easy still to fall through. They were normally only left open for short periods or just as the catering trucks were due to arrive. It was useful in hot destinations to open the door to get some breeze through the cabin. (I was cabin crew on them for several years)
The lower open doors are of course the baggage holds.