I'm fairly sure it's not kids. Which makes me even more annoyed.
When I first moved into this house, hamburger gave me some hosta cuttings - most of which I put in the front. I got up on a couple of mornings to discover they'd been dug up!
I moved the survivors to the backyard, so I could have a hosta nursery - and moved them out front when they were bigger and more difficult to dig up and walk around with.
The gardeners can be pretty aggressive around here.
One of the reasons I'm sure the cherub theft is a gardener is that you had to look very carefully behind the squills, and in front of the lungwort, to see the little character sitting on a 2-brick high mini wall. You'd have had to be very interested in the plants, and looking at the garden itself.