One indication that this isn't B2B is the use of WorkMarket instead of dealing with gig workers in a B2B fashion. The stated value-add of WorkMarket is to allow businesses to manage their "freelancers and independent contractors".

So businesses take a cut out of the budget to hand it over to a "management" company to sort out the paperwork, and they require their gig workers to provide liquidity to the client business via net30/60/90 terms.

One has to be blind or stupid to call this a B2B relationship in the sense of two equals dealing with each other.

Yes it's completely normal. The author has no idea what accounts receivable looks like at most companies.