Well, you already gave yourself the answer: Germany is a federal Republic
And the DFL is not yet bigger than local health authorities, so when Saxony allows XXXX people for events and Bavaria does not, thats just something we have to live with and I think it's fine. Because if it goes well in those places, where there are spectators allowed, it's more likely that the more strict states will allow spectators as well. Someone has to be the first to test (successfully) for others to follow
I don't see a big issue putting a few k specators in a stadium tbh, since it's outdoors and you will not have packed stands. Just hope that there will be some hardcore fans as well to have a bit of an atmosphere again. Just 500 of them are already enough, to get some more football vibes after months of lab conditions in the stadiums. Only two weeks to go until 1./2. Bundesliga start again and I am already excited
Sure, the DFL wouldn't be the one that have to decide that but the politicians could have put their foot down and set up a common rule for all stadiums.
Btw. just today Jens Spahn, the German health minister, did also criticize the current situation with different regulations all over the country. He would have very much liked "that we have a common approach for the start in the Bundesliga by the end of October" (
Source).
As much as I am excited for the start of the next season and for the fans to come back to the stadiums (to create that unique atmosphere), I still have the feeling that all this is a bit rushed. Because once fans are allowed back in the football stadiums, other events (like concerts etc.) would like to follow that example understandably. And all that without the whole pandemic fully under control seems very risky to me.