Do gays get a pink wheelie bin?

Birmingham council do have somewhat of a reputation for bureaucratic stupidity. They recently sent out a questionnaire designed to find out people's attitudes to refuse collection and recycling.  Nothing wrong in that, you would say.  Until you get to the last question - Which of the following most accurately describes your sexual orientation?  You are given the option of choosing bisexual, gay man, gay woman/lesbian, heterosexual/straight, other and prefer not to say.  Can you see the connection here because blowed if I can?