I'm guessing maybe the tradesman using old Volvo estate cars aren't VAT registered? That was certainly the case 30+ years ago when I was on the tools & working on site and VAT on commercial vehicles was an expense few trades could recoup.
But now in my locality the tradesman are more business savvy & the prevalence of easier finance on new vans means the old estate cars have disappeared from site. Its almost a badge of honour among them that they do have a new van!