Our local RSPCA runs free chipping events, Im waiting for them to extend this beyond cats & dogs to get ours done.
As yet I have to say Im not too sure what the chances are of them actually being scanned should they be found.
Ive had my rabbits identichipped ever since they first came into use.
I know plenty of surgeries that do and some rescues/wardens that do but it seems that many rescues don't have a scanner which is a shame
the identichip companies should give them all a freebie
Perhaps some rescues should try arranging this, maybe have a day of discount chipping at a rescue open day and the rescue gets a free scanner - all good publicity for the identichip company!
I'd never heard of vaccinating rabbits when I first got them but it's done more and more often now, so if people get involved with microchipping it might become more the norm/expected thing