> Washing machines did not exist until recently either, but no one in this thread is advocating hand washing their clothes.

This conversation is about people being denied the right to do something, the reasons why they should have the right to do so are there to justify it. No one said people should not be able to wash their laundry by hand. It is probably because doing so is unobserved. That being said, it is also a much more challenging thing to advocate for. While hanging one's clothes is marginally more labour intensive, washing clothes by hands is much more labour intensive.

> In the US dryers and washing machines are a set pair.

I understand what you are getting to, but the presence of both does not imply that both receive the same level of use. For some people, the use of driers is purely seasonal. For others, it will only be used for large items or things that need to be dried quickly. As for the examples of laundromats and shared facilities, the complimentary pair is intended to attract customers (not to mention that hauling around wet clothes is a pain).