Depends on jurisdiction but practically, yes, and in fact in California the EDD was systematically suing local governments to convert taxi drivers into employees (and to recapture lost taxes they would have billed had they been employees) until Uber blew that system out of the water. Source: was taxi driver in SF / CA during that time. And as a practical matter, yes these folks met all the checkboxes of being employee despite the assertion otherwise by taxi companies and cities.