I work for a contractor supply company. The majority of our business
is on credit to contractors. (more than 70%). We also have retail
locations and a truss manufacturing facility that fill the majority of
the remaining 30% of our revenue.

Contractors are able to get credit to do projects if they're reputable.
Their suppliers also rather that they "run a tab" for all materials
on a project so we can send them a bill for that project at the end.