Even more confusingly, it's not consistent about the measured dimension. The car is 1.8m (wide), the firetruck is 2.3m (wide), the tractor is 5m (long), the bus is 12m (long), the statue of liberty is 46m (high), the astrodome is 66m (high).
It would have made more sense to stay with either height or the largest dimension (but that would have been weird for mountains, which often are far wider than high).
According to Wikipedia, Saguaro cacti "can grow to be over 12 meters (40 feet) tall". So, a real old and real huge Saguaro can be bigger than your average house (or palm tree): https://en.wikipedia.org/wiki/Saguaro#/media/File:Saguaro_wi.... But I would say 99% of them aren't...
It would have made more sense to stay with either height or the largest dimension (but that would have been weird for mountains, which often are far wider than high).