My job title, as it was printed on my employment offer and paycheck, at a start up that was located a few blocks away from the Google HQ in Mountain View in 2014 and staffed by plenty of xooglers, was "Front End Hacker". Six figure job.

Not that it disproves your statement that the titles are uncommon, but hey, I just want to stand up and say "Hey, us professional hackers and ninjas and cowboys are REAL!"