There are laws about what constitutes contractors vs employees - both federal and state. If you satisfy N out of M items in a checklist, you are an employee, regardless of whether both parties want you to be.

Controlling how you do your job is one of them. If the employer directs how you can do the job and doesn't give you freedom to do it your own way, that's a major item.

If your employer doesn't let you bring your own equipment, that's another one.

If you do not have a chance of losing money on the contract, that's another one. Say you hire a contractor to repair your roof, and he screws it up. Typically he is expected to fix it even if he ends up with a net loss (or he can refuse and not get paid at all). When an employee screws up, the worst that will happen is he'll get fired.

And so on.

It's very unlikely these people can be contractors unless he's hiring experienced folks who know the equipment.