Yup, I agree, there is probably a very short production time, with tight deadlines. But still, it doesnt make silly and very simple errors like this acceptable. How long does it take to check something this small?
I used to be in the advertising line, and while ad agencies will try to highlight possible mistakes, the company putting up the ad must approve the final artwork and copy.
For example, if it is seem to be offensive or inappropriate, the company bears full responsibility, not the ad agency.
To tear out the existing ads, reprint new ones and stick them on all the buses again would cost. Whether to bear that cost would depend on whether Nikon deems it economically viable against a bad corporate brand and image.
This "Sh!t" seems to be happening quite alot (not just with Nikon) maybe people are just being lazy or the advertising agencies cant copy things right, or they are given already bad copies by the respective companies.