I think that there is some form of high pressure sales going on here.
I'm not so sure.. maybe in some cases but certainly not all.. Me and a couple of mates got offered some work with Irish travellers when we were in our late teens.. as we were living in a caravan in a carpark it seemed the next logical step, so we let 'em hitch us up to the back of their transit and tagged along..
One of our jobs was hawking.. the only sales tactic was to put on a hi-viz jacket and knock on the doors in wealthy neighbourhoods, trotting out a well rehearsed speech about working the roads in the area with spare tarmac to use up..
We always managed to pick up a job or two per day, I wouldn't say any of our sales were to vulnerable folk, and there was certainly no pressure selling, we were too young and nervous and polite to know how..
People just love a bargain, and I think there were even a few who were simply waiting for the pikeys to come knocking before they got their drive fixed
The lot I was with weren't exactly consistent in the quality of their workmanship though.. some jobs were very good, but I remember us having to leave town after a large carpark at a private nursing home was starting to sink and crack under our feet even as the guy was handing over the cash at the end of the job..