If you're asking socially, you don't, that's the benefit of writing laws instead...

If you're asking socially, you don't, that's the benefit of writing laws instead of programs.

If you're asking technically, well, google made over 400 billion dollars last year, they can spend some of that to figure it out.

Or stop serving ads. Just because it's difficult to do safely doesn't mean you get to just do it anyways because there's profit involved.