In reply to Offwidth:
In all seriousness is there something about how people are signed in to revisit here?
When someone signs in a roped climber, they are taking full responsibility for their safety. This is quite easy to do, because they don't climb without the person who signed them in belaying (or some other competent climber who's signed off to belay), and walls do ask questions if a non-signed-off climber is belaying without being tailed (as I experienced once when someone belayed me who wasn't signed off - not deliberate on my part, but I didn't realise he'd been signed in by another person - maybe there's a case for having US-style harness tags to avoid such misunderstandings if they are in practice causing accidents).
Bouldering is different, because if you sign someone in for a boulder you tend to go on and climb with them, and while you might spot them while they climb when you do they then wander off, and as there's no physical rope to hold there isn't the same motivation to ensure the supervisor remains on the ground - nor the same need. It's also the case that bouldering briefings are done by most walls on demand and only take a few minutes. It's also reasonably obvious to a floor walker if bad belaying is going on, while it isn't necessarily obvious that a briefing about falling hasn't been given.
Therefore, there seems to me to be a reasonable case that if signing in a novice, they should receive a briefing from staff and sign a sheet (with questions to check they have read it[1]) to say they've read it, even if being signed in by another person, before they do any bouldering. If roped climbing only, that shouldn't be necessary, but it would depend on the wall's layout as to whether that was practical or not (i.e. whether staff would be likely to see it) - at Big Rock (MK) they would, the bouldering being the bit most visible to the desk, but at, say, Pinnacle (Northampton) they wouldn't as bouldering is in a separate room hidden away from the desk, and picking out people via CCTV is hard.
Big Rock sort of do this in that they don't allow bouldering-only members to sign people in - but is there a case for extending this to roped members, i.e. you can only sign people in for roped climbing, and all boulderers must receive the wall's briefing for new boulderers before taking part?
[1] One wall I've come across hides something silly in the standard ABC briefing text - something ridiculous (though I can't remember what it actually is) like "geese are only allowed to climb on a Wednesday". Having something like that is a very good way to ensure they actually read it - partly because you'll normally see a grin as they do read it, and partly because you can ask it as one of the briefing questions, so someone who's seen lots of ABC/BMC rules sheets before still has to read it!
Post edited at 10:14