Facebook has many illicit groups and Mark Zuckerberg was never charged with anything. I assume this is more related to privacy where US government has backdoor to Facebook while doesn't have one to Telegram.
So yeah, Meta takes it really seriously. It doesn’t work perfectly because the scale is mind-boggling, but it’s probably the best system of this kind at this scale, and it is constantly being evaluated, red teamed, and improved.
Source: I used to work on FB Groups.