I've done arts festivals, for over 15 years, all of which are juried. I'd estimate I've submitted over 300 times in that time span.
It's true that it's mostly (not exclusively) done by scans now. A few will accept slides, and some will look at prints. The vast majority are digital, though.
I preferred when it was slides. Analogue (especially monochrome) photographers are at a disadvantage, as their work is another generation removed from the original. In speaking to jurors, over the last few years, most of them stated that the analogue work they see at shows is much better than the scans they juried with. Jurors who had juried shows when slides were the norm were especially aware of the differences. In my case, I generally display large prints (20x24 inches) but need to make a print no larger than 8.5 x 11 for scanning purposes. This size doesn't allow for the control of dodging/burning/toning in my work. Alternately, I can use digital to photograph a large print, but that has issues, too.
As an aside, the improvements in digital, over the years, has substantially increased the number of submissions. 15 years ago, you had about a 1 in 10 chance of jurying into a good show in the photo category. Today it's closer to 1 in 20 or 25.
A few years ago, there was some talk of separating analogue from digital, in the photo category. I don't think it went very far...