Even drawing research rolls in more money than this.
Requires even a modicum of talent however.
Also generally need to have produced a small amount of work beforehand to get any interest, which depending on your skill, may take you lots of hours. And there's the cost of whatever materials you use, whether you actively draw in pencil/ink, or are solely digital, and what tablets or scanners you possible use.
Whereas if I were to work a regular 8 hour shift at McDonalds in the UK, I'd earn a minimum of £41.04 (at age 18-20) or £52 (at age 21+).
£5.13-£6.50 an hour isn't bad for a low-skill job.
But I suppose yeah, if you were talented and had the necessary equipment and facilities to make art (researchographic or not), then you might do reasonably well.
I don't know if it's the average, but I've seen researchographic artists charge $100 for an individual picture before, so that's £66.50 for I don't know, let's say 3-4 hours perhaps?