I wonder why

Protection from the sun?

If they are historical photos (which it looks like they are), then that's a reasonable hypothesis

The ideas I could come up with are 1. Glare…but they aren’t very large photos and don’t get a lot (if any) sun hitting them or 2. To protect the photos somehow…but I’m quite sure they aren’t special photos worth protecting.

That's probably what, plus when sun angle is just right, they probably blind people sitting at certain tables

All it takes is 1 or 2 people complaining about glare, and that's that. Solution is blinds

Is there something offensive about the photos?

The sun's glare off the glass at certain times of day probably disturbs patrons

I can’t imagine so, the photos are of old shops and streets and such.

I’d probably chalk it up to this, but after looking a bit more, there are blinds on other pillars/photos in the restaurant that I’m almost positive will never see the sun. I assume if it was glare from lights in the building they’d need to be covered all the time.

I’d probably chalk it up to this, but after looking a bit more, there are blinds on other pillars/photos in the restaurant that I’m almost positive will never see the sun. I assume if it was glare from lights in the building they’d need to be covered all the time.

The glare off the glass wouldnt be the problem. When they clothes the shade it’s now a blinding nuclear white light