Can you maybe add some actual legal details here? Because as far as I know cannabis is indeed illegal on the federal level in the US, too. Which is the whole point they try to change here.
Just like in a lot of US states, several EU countries have legalized it to the point where it's legal or at least decriminalized on the consumer level. But that doesn't do shit if production and sale aren't legal on a bigger level as it either breeds a criminal network in the background doing the logistics or just scattered local and private production often also cut of from the financial system completely as on that federal level cannabis is still illegal.
So the actual point here is legalization on der German federal level and also comply again with the bigger EU legal frameworks. To get rid of the black market and to get cannabis production and sale regularly taxed and controlled.
The difficulty is not some imaginary conservativism in Europe or Germany or misconceptions about the dangers of cannabis. It's simply not doable without bending and working around a lot of existing laws and regulations including even the UN's Commission on Narcotic Drugs.
For the same reason you might have some states where cannabis is legal for a decade and more that half of all states having it legalized in the meantime by now. But you are also still far away from actual legalization in your whole country and on the federal level as the US has also bound themselves to decades old UN and other agreements that categorically prohibit legalization.
That's also the whole reason it took that new Germqan government full two years for the first (and very restricted) draft of a law when what they wanted was full legalization. Not only are single conservative German states fighting tooth and nail against a German-wide legalization, but their plans were also constantly shut down by the EU as incompatible with EU law. And other countries in the EU aren't helpful either. Some went for their own and also very flawed way of just decriminalization and the ones open to legalization just watched for years now hoping Germany will do the work and solve the issue with the EU.