Tech companies have tried this in the past, now this would typically be met with an antitrust suit rather than creating a guild. Not sure which is preferable.
With a guild/union: grievances are addressed immediately or before they occur (depending on the structure of work contracts), minimizing the economic suffering to employees.
Generally, from the perspective of employees, guilds/unions are better.
EDIT: a "guild" is a union for independent contractors.
The list of reasons unionizing drivers would be difficult to impossible is long and obvious, but the outcome would surely be better than some hamfisted state law.
Also, right now uber is framing the issue as drivers vs the state. A union push would make it uber vs the drivers, much harder to spin.
The state could mandate sectoral representation for all the drivers, functionally requiring unionization. That way the nitty gritty details are still just contract negotiations between the union and the gig economy companies, but there isn't too much space for overly broad or stifling regulatory requirements (from the State anyway, between the lawyers on all sides of the issue is a different story).