I would guess higher but it's based on personal experience. Compared to freelance software devs, I know a lot more "sole proprietor" handymen type guys, i.e. they specialize in bathroom and kitchen renovations, or other "home improvement" jobs that one guy can do by himself or maybe with a helper.
The real tradesmen (plumbers, electricians, etc.) will often start their own businesses, especially once they get to know and be known by the local contractors, and end up doing bigger new construction jobs with dozens of employees. The comparable white-collar version of this would be the experienced developer or marketer who starts their own consultancy or agency.
I think it would be more rare to see a true "start up" in the blue collar world. Most of their work is regulated by code and there isn't as much room to compete on innovation, you have to compete on reputation and experience and that can't be substituted by VC money.
