Uniforms are pretty common in Santiago, as well.
I know a few nannies whose kids attend very nice private schools because their bosses pay for it as part of the "package."
I've always said I can tell the type of person by how they treat their domestic help here. It really is ass backwards to treat your domestic help poorly - they carry ALL of the secrets of the family whether you think so or not, they are who your kids trust, etc...
As far as this uniform law - it's ironic that the pro-domestic-help movement was started by a wealthy woman whose perspective is that the uniform is embarassing - that part of the law didn't come from the actual workers. And we're stuck on uniforms, but the new law gives domestic workers more rights (health insurance! paid maternity leave!) that they weren't necessarily assured of without this law.