I'd love to have the equivalent of paternity/maternity leave as someone who never had kids.
An equivalent for someone not having kids would be taking time off to volunteer somewhere.
Or taking time off to go out in order to find a partner to potentially have kids with...
Your second point makes sense, but many don't offer that. Some do, some don't. Often volunteering is seen as a thing one gets compensated for (donation to charity) for work you do outside work time.