A consulting visa would set up perverse incentives between employers and "consultants"; I don't see what the public policy difference is between someone working W-2 and someone working 1099, except that in the 1099 case the employer has an excuse not to pay FICA or offer health insurance.
A problem with startup visas is that nobody knows what a viable startup is, and countries have a strong incentive not to offer long-term residency to people who can't support themselves. So what we have to go on instead are proposals like "we'll allow you in if you're sponsored by a qualified venture capitalist", which creates it own set of perverse incentives.
All things being equal, public policy usually prefers employer-employee relationships over 1099. Tax collection is more sure, worker's comp and unemployment get paid (and the individual is covered), etc.
Probably the best way to deal with "startup visa" is to instead have a small-business visa. Small-business already has an understood (to the government) meaning, and there's already a lot of examples of slightly different rules for them.
A problem with startup visas is that nobody knows what a viable startup is, and countries have a strong incentive not to offer long-term residency to people who can't support themselves. So what we have to go on instead are proposals like "we'll allow you in if you're sponsored by a qualified venture capitalist", which creates it own set of perverse incentives.