I've never understood this part of it. There's a disinformation problem on all of these platforms, so why not just kill all of them? The only argument I've seen is basically that it's better for the West to be the ones manipulating people in the West vs. having people in the East manipulating people in the West. And that just doesn't feel like a good argument.

People in the culture that they live in have a vested interest in it.

This is only relevant if people are manipulating others for the betterment of the culture, and that feels overly optimistic IMO. If everyone is just manipulating for selfish reasons, they'll happily destroy their own country.

As the politicians of the US have shown time and time again /s

Why wouldn’t that be a good argument? You might as well ask why the US president is required to be a natural born citizen.

As much as there are legitimate reasons to go after TikTok, I can't help but feel it's not a coincidence that it gets singled out for legislation because it's the only one owned by China.

And yes, that ownership is problematic but I would argue that the others including those you've listed here are equally problematic for the safety of users.

So to answer your question: they should be too, but they likely won't, because the force behind this isn't a desire to protect users from disinformation, the desire is to protect western companies from scary Asian competition. Same reason behind us constantly propping up Detroit. Protecting people from disinformation is just an excuse.

> I can't help but feel it's not a coincidence that it gets singled out for legislation because it's the only one owned by China.

Of course it's not a coincidence. It's not even a hidden, implicit unspoken motive, it's openly explained as the reason behind the concern! TFA explains this clearly, numerous times.

You'd have to ask Mark Zuckerberg and Elon Musk about their agenda for America, and for Americans.