There seems to be an awful lot of fluffing around the issue here.
Sadly, the world is a grey and fluffy place - not as black and white as you might like.
The airside driver must have an airside driving permit and vehicle RT certificate.
You seem to be making some assumptions here about what having these bits of paper signify and just how much competence having permits and certificates actually represent. I mean no disrespect to those who hold such bits of paper, but training and standards do vary.
If he has crossed a holding point (his training would have taught him what this is) then he MUST NOT re-enter the runway without clearance.
Now here I'm getting a little puzzled - maybe your training was different to mine - but where does it say that?
It is of no relevance that the tower controller should have foreseen a potential problem (there is no requirement to)....
But isn't that a large part of the job? Isn't it good practice to look out for potential problems and do what we can to stop them becoming actual problems. Granted, there is no actual requirement to foresee what could go wrong, but it's a bit of a difficult one to enforce. On the other hand, there are plenty of requirements these days to manage risk.
....and there is also no requirement to report vacated.
Ahh, finally something we can agree on.
Having said that if a vehicle is cleared to operate on the runway it is good practice to report vacated....
So which is it to be? There's no requirement to do something, so don't do it, or do good practice even though there's no requirement. Do I detect an ever so slightly double standard being applied here depending on whether we're talking about a controller or a driver? And where on this scale of standards would a pilot fit - or would it depend on whether it was a PA28 or a B744 that he or she was piloting?
....but the fact that the tower controller saw him cross the holding point makes it perfectly acceptable to clear an aircraft to takeoff/land.
I'm a little unsure about this. I'm inclined to think that it would rather depend on the clearance that the tower controller issued. We seem to be making an assumption again here, and you know what they say about an assumption.....
Grass roots fact is that the driver is at fault (it's a runway incursion). MOR it, accept it and learn from it.
Perhaps it's just an unfortunate turn of phrase but your first sentence seems to imply that if it's a runway incursion then the driver will be at fault. But I'll make an assumption (it's safe to do that here because this is just an old fashioned message board, not real life) that you mean that, in this example, the driver was at fault. But now I'm thinking that this isn't a very 'just culture'ish thing to say. When something goes wrong, aren't we supposed to try and understand why it went wrong and try and do something to stop it happening in the future? And if, our errant driver (or whomever) made an honest mistake, we don't penalise him or her. And when it comes to runway incursions, if you look at the data you'll find that there are few instances where there is a single cause but rather, more usually, a combination of contributory factors often made by a range of players (some of whom may have made their contribution months or even years ago). So there may well be something for the controller to learn from the event also, if not others. But I guess we're back to some of your earlier comments which suggested that the controller will not be wrong....ever.
A word of advice, go and look up a bit about TEM - it's a good principle in our business. Then take a bit of time to analyse your controlling techniques. Maybe listen to a few random periods from the tapes and see if you are making assumptions that may be incorrect. And think about how you could stop things going wrong if your assumptions are incorrect.
I do hope your post was intentionally provocative and designed to prompt discussion. It would be truly frightening if your comments truly reflect your thoughts.