To a newbie 6k per month per van sounds eye poppingly good. However if you break it down and spread it between four workers (five if the owner is off the tools) then it's not a huge leap from a sole trader.
It's very good in Alan's case as it gives his son a good living too, far better than flipping burgers etc.
You also need to look at the bigger picture like making enough profit to fund a newer van, replacement tools, new systems, tax, holidays etc.