Just doesn't really seem worth it.
I've got an unskilled job for £9.10 an hour, £10 if I worked nights. Before I got that this year I hadn't worked in a very long time.
I'm not away from home like some drivers are, don't have to put in the long hours, don't have to have licenses/qualifications, don't have to comply with as much regulation, am unlikely to kill people if I make a mistake, don't have bosses pressing me to keep time whilst driving economically too etc. and I'm not far off earning what they do.
I also get £18.20 an hour an bank holidays so I'm ahead there.