As someone who has worked at 501(c)3 orgs that have launched public interest lawsuits, they are very likely receiving money to pay for those cases. And probably

As someone who has worked at 501(c)3 orgs that have launched public interest lawsuits, they are very likely receiving money to pay for those cases. And probably the majority of funding for a case comes from just one source--a source you likely don't know is funding it. Just because you see the ACLU or EFF doesn't mean you see where the money is ultimately coming from.