Bloggs,
You've hit on a particular bug-bear of mine.
Virtually no where else is it legal to shoot an approach past an approach ban point with conditions reported below minima, as Chimbu has said.
As an FO in Aus, though, I more than once had Captains who would "Take a look" when conditions were obviously below minima. In my opinion this was illegal as there was no "reasonable grounds" to think they would be able to land, but it was never questioned and was a cultural norm throughout Aussie airlines.
I believe Qantas has instigated the equivelent of an approach ban in recent years, and good on them for it.
It is very difficult, IMHO, for anybody except the flight crew to know what can be seen at the designated minimum.
True, but if the vis is below minima before they ebven start, they shouldn't be there!!
If we could now just convince them to always carry an alternate.....