As a Scout leader we sometimes have children who can’t appear on photographs full stop, for various reasons, including legal ones sometimes. You just keep it in mind before taking pics. Obviously, you just need to be careful about taking photos, so the kids don’t notice your singling anyone out. It’s certainly not our place to question it.
I’m doing our display board at the moment, & each child has a little characature with their face on to mark their progress, but one or two are left blank. For Beavers, I try to get a mugshot, as (God forbid), if one ever gets lost on a trip out, we have a pic on hand for obvious reasons.
We use social media but only in a closed group with as leader as admin & everything locked down, so any posts get vetted before they appear. It can be a bit OTT but you have to respect people’s wishes.
My children are on FB occasionally, but I’d be very concerned if an adult shared or tagged them specifically, especially at a young age.
As regards using pics for a web site, I’d probably not see it as s problem.