It's extremely unrealistic to sue someone for violating your Terms of Service. It's not impossible -- you'd need to sue them for a breach of contract and demonstrate clear financial damages --, but the primary solution is to just refuse to provide them service.

Like, Reddit may know that Bazzly is selling fake comments, which violates Reddit's ToS. How many comments can they prove are tied to Bazzly? How much does an astro-turfed comment financially harm Reddit, and can they convince a jury of that?

Instead, most companies will aggressively shut down the bot networks, if they can identify them, and hope that the astro-turfers focus on other platforms, and/or make it more financially challenging to do it successfully on theirs.