It matters because everyone - people, companies, countries - is supposed to be equal in front of the law. Selective application of the law shows this not to be the case and shows that there are other factors in play which decide whether someone - a person, a company, a country - gets to violate some law without legal consequences while someone else is prosecuted for the same violation.

If you now think "they have to start somewhere in prosecuting these violations" you're partly correct but also partly mistaken. Sure they have to start somewhere but they could - and if they are really serious about their claims should - have started prosecuting all those other companies which did this way before TikTok or even its predecessor Musically was a thing. Algorithm-driven endless scroll designs to keep user's eyes glued to the screen have been a thing from very early on in nearly all 'social' app-site-things and the warning signs about addictive behaviour in users have been out for many years without the law being thrown at the proprietors of those entities. As to why this has not happened I'll leave for the reader to decide. There are plenty of other examples to be found in this regard ranging from the apprehension of the Telegram CEO to the sudden fervour in going after X-formerly-known-as-Twitter which seem to point at politics being at play in deciding whether a company gets to violate laws without being prosecuted or not.

So what's the solution you ask? As far as I can see it is to keep these companies from violating user's rights by keeping them in line regardless of who owns or runs the company and regardless of whether those owners or proprietors are cooperative on other fronts. Assuming that these laws were written to stem the negative influence these app-things have on their users they should have gone after many other companies much earlier. Had they done so it might even have led to TikTok realising that their scheme would not work in the EU. They might not have launched here or they might have detuned their algorithmic user trap, they might have done many things to negate the negative effects of their product. They might just have decided to skip the whole EU market altogether like many other companies have done and do. I'd have thought 'good riddance', what you?