@Account Closed let me see if I can address your curiosity. I think it boils down to 'do as the local custom does'.
When we were in CT, it had state-wide licenses and we stuck with licensed companies for plumbing, electric and large jobs, but did have an unlicensed handyman we used for minor stuff (also we had a fair amount of insurance...).
In New York state, there aren't state wide licenses. Some municipalities that don't require a given license also don't have a clear mechanism for issuing said license. With no state-issued licenses, you'd be getting at least 4 separate licenses in our area. So licensing seems to be viewed as an unnecessary expense and hassle by all but the larger (10+ employee) operations.
The size of metro area may also be a factor. Our cost of living is low enough that you can make a nice living as an HVAC contractor with one main helper. The smaller electric and HVAC contractors that we use are not licensed but they are insured. Also, it's a small enough area that references work (folks will tell you what they really think of the contractor - and contractors talk to each other as well).
Related topic - pulling permits. I assume this is the case in most areas, but here you can't pull a permit without workman's comp coverage (or a waiver). And most contractor's insurance covers them only if they have pulled a permit (if a permit is required for the work). So if you are paying someone else to do work, err on the side of getting a permit!