Why don’t California farm workers or domestic workers get overtime pay?

Bills are headed to Governor Brown’s desk for his signature that could affect two groups of California workers who aren’t now entitled to regular overtime pay. One would make overtime kick in for farm workers after eight hours of work in a day, rather than 10. The other would make a temporary overtime law permanent, guaranteeing domestic workers overtime pay if they work nine hours in one day and 45 hours per week. Most hourly workers get overtime after eight hours. So why have these two groups been excluded?