Germany has banned RT, apparently because it is considered to be not independent of the Russian government (Die Medienkommission sieht die Staatsferne nicht gewährleistet), which funds it directly. In response, Deutsche Welle was banned in Russia. Meanwhile, France24 and Voice of America, which are also state-funded, are allowed in Germany (among others, probably). Why is RT prohibited, while other state-funded foreign broadcasters such as France24 and Voice of America are permitted? Is the ban based on the contents of the RT broadcasts, or is there another critical difference as far as German law is concerned?
First a little clarification: It's not the original English-language RT which is banned in Germany. The English version of RT is actually available via satellite and in some regions of Germany via cable for quite a while. The fuss is about RT Deutschland (RT DE), the new German subsidy of RT operating from their offices in Berlin and producing a German program in Germany aimed specifically at the German audience.
Here is the official German press release by the regulatory body which banned RT DE (Kommission für Zulassung und Aufsicht der Medienanstalten, ZAK - commission for permission and monitoring of media institutions). They justify their decision based on a technicality.
TV stations in Germany require a license in order to operate. They first have to request a license, and that license needs to be granted. The ZAK did not grant such a license to RT DE because so far RT DE did not request a license with them. So RT DE is not allowed to broadcast in Germany.
RT DE did try to obtain a license to operate in Luxembourg. This failed (German article), because the government of Luxembourg considered themselves not responsible for licensing a TV station aiming primarily at the German market. They then applied for a license in Serbia (which succeeded) and claimed that this license would allow them to operate in all of Europe (Serbia is not an EU member, but a member of the European Convention on Transfrontier Television). The German regulatory body, however, did not accept that license and insisted on being asked for one themselves.
Why doesn't RT DE try to get a license in Germany through the official channels? Likely because they assume that they would not receive one. But an official statement of why exactly would require that they try. Until then, it would just be speculation.
I did not check, but I would assume that VOA or France24 either did request and receive the required license, or don't need them because they don't broadcast via the channels monitored by the ZAK.
There is a lengthy list of criteria in §1 Medienstaatsvertrag to describe which broadcasters need a german licence. It would take a lawyer to really paint an adequate picture, but I think the main reasons why France24 or VOA do not need a licence is because neither of them
- offer a program mainly aimed at a german audience and
- produce or control their program from an office in Germany.
RT DE does both, so the distinction is quite clear.
There are the stated reasons and there is realpolitik. Ideally, all Western countries would ban RT in all its forms. RT is very popular in the West and excels at making readers and viewers question their own governments. The only reason we don't shut down RT is that it would lead to Russia shutting down our channels in Russia, and we deem that cost too high. But here, Germany was able to use a technicality to stop the channel and say: "hey, it's not us, it's the technicality!" The Russians haven't bought it, though, so it will be interesting to see if both governments decide to re-open the other's channels or if they leave them shut. To some extent, this is similar to the problem of Nord Stream 2. Germany has been under tremendous pressure in the West not to activate it. It has used a technicality to stop the pipeline from coming to life, despite the enormous cost on Western consumers.
The other answers offered technical reasons, but they don't provide the fundamental reason, which is perhaps so obvious it's unnecessary to state. The fundamental reason is that the narrative put forward by RT DE would undermine the legitimacy of the German government (and more generally, the current Western European political system). France24 or VOA do not, and in fact reinforce the status quo.
Regulations are always complex (sometimes even contradictory) and thus difficult (or impossible) to fulfill. This means that regulators have significant discretionary leeway to find a "reverse loophole" that allows them to achieve a desired policy objective. Given the geopolitical tensions between Europe and Russia, it's unsurprising that German regulators would prefer to minimize the ability of the Russian government to promote its own message to domestic audiences. This is especially the case since the Russia generally prefers the outer parties in Western European politics, while administrative personnel are generally aligned with the mainstream parties.
Propaganda that endangers the current stability or legitimacy of the country, society, people is most often identified as such and blocked. Propaganda that is not dangerous this way is usually just ignored, even if it is biased, inaccurate, wrong and generally not worth listening.
Democratic society seems having some complex ability to differentiate between very blatant propaganda and somewhat more independent and objective analysis.