IIRC the EU standard won't let you certify (OTP?) racks to more than 25 kg, but I'd have no problem giving backies on my Dutch bike - I reckon the rear wheel is going to start breaking spokes before the rack gives way.
Ah, I've probably misremembered the limit; it may be 35kg. I know it's significantly less than the weight of the average adult - the makers of my bakfiets explicitly said something like 'we're not allowed to tell you you could carry a 6'5" Dutchman on this rear rack (nod nod, wink wink)'.
IIRC the EU standard won't let you certify (OTP?) racks to more than 25 kg, but I'd have no problem giving backies on my Dutch bike - I reckon the rear wheel is going to start breaking spokes before the rack gives way.