There is definitely a distinction between the legal requirement to carry workers comp and the practical reality of not having it. If someone pays you to do work and does not verify that you have workers comp (even if you’re excluded on your own policy), they are legally obligated to pay for injuries you sustain.  Even if you don’t have enough employees to trigger a legal requirement, it is a perfectly legitimate request on the part of your customer to protect them from potential liability for you and anyone you may hire.