Some dont even seem to know about jetting... Also a few that like to upsell jetting, CCTV and a drain repair, presenting a 4 figure bill, when all that was needed was a good poke with some rods. (Usually Elderly customers, panicking because their only toilet is blocked. )
All joking aside, it is a specialised area, and you need to know what you're doing. Having done HPWJ Training and seen the safety bulletins, there is a lot than can go wrong, at best you could blow a customers Toilet, at worse it can take half your face off....