Once they catch up with them they will say naughty naught don't do it again.
What I would do is find them and get them to do some work in the community, bit of road sweeping or something like that auntil they have worked enough to pay back for the cost of the glass.
Mindless vandalism like that is something that really pissses me off no end. Not far from where I live, a defibrillator was pulled from its holding bracket and thrown into the sea a couple of months ago. The thing about this kind of offence - There really is a punishment to fit the crime. i.e. Those that cover walls with graffiti should be sentenced to cleaning their handywork up at weekends plus other suitable punishment. Make the scumbags wear a high viz jackets with 'community payback programme' or similar. Humiliate them as much as possible! The Council workers empty bins around the towns and cities. Make the vandals scrub down the insides after they are emptied and clear up the residue. Scrubbing seagull and pigeon shit from the pavements. Plenty of options for the nasty little scroats.