Three reasons:­

  1. Historic Model – if you are a small or medium contractor you may only need the specific skills of particular tradesperson for a relatively short period of time – so the modern way of working has more than a passing resemblance to the historic transitory nature of an artisan tradespersons way of working where an individual goes from site to site, depending on who has work available, and
  2. Simplicity – it allows small and medium contractors to avoid much of the complexity associated with employing people, especially if they are only needed for short term engagements, thus allowing contractors to more easily align workforces to workload, and
  3. Costs – there are cost benefits for both the contractor and the sub-contractor – the cost of engaging a self-employed worker is up to 40% lower than that associated with employment, so the contractor can reduce costs whilst paying more to the self-employed worker, who in turn has far greater control over when and where he works.