That might be a temporary situation: currently, most homeworkers are such because they were already contractually strong enough to command such a big adjustment in work conditions, so of course they are not the ones who'd want or need unions.
As these arrangements become more and more mainstream, I'd argue that it might actually become easier to organise homeworkers: when you don't have to fear the physical presence of your managers or their anger, relationships become somewhat more academical and dispassionate.
How would they ever agree on an acceptable minimum rate? Somebody working from SF will have a dramatically different view on living wages than someone from Bucharest or Mumbai.
As these arrangements become more and more mainstream, I'd argue that it might actually become easier to organise homeworkers: when you don't have to fear the physical presence of your managers or their anger, relationships become somewhat more academical and dispassionate.