Re: So what about
'It seems to me that no one is much worried about people in the gig economy on good money; it's only those exploited at the bottom of the payscale that need protection.'
So you have to ask yourself why do people capable of earning good money choose to do so as independent contractors? And from there ask yourself if those at the low end are really being exploited or they simply don't have the skills to be higher up the pay scale.
Force a business to pay more than the job is worth and eventually the job just doesn't exist.