It's probably easy enough for a painter immersed in the job to simply call for the next stencil and get on with it without paying attention to what is actually being applied. And if the airframe is due in service hours later there is no time to fix it.
I am intrigued though that one is deemed spelling "police" to flag up such a blatant error. In the first instance it is clearly a mere typo, not a spelling error at all and even if it were spelling it is hardly "police" action to point out something so ridiculously blatant?