If you do a quick job search, those places have the most jobs in Auto and also the highest wages.
For the US it usually means some successful SV FAANG type software company.
For Germany it's usually some successful hardware engineering company (Siemens, Bosch, Mercedes, Arri, Infineon, Continental etc.). Those companies can afford to pay the equivalent of FAANG wages in Germany albeit at a smaller scale.
Southern Germany has more experience and talent in the latter while Berlin has more software startups and web devs, similar to the former.
There is also a steady supply of students from that branch of tech - AFAIK AutoNOMOS Lab still exists and there are multiple universities in town that over computer science focused on embedded systems.
https://www.thelocal.de/20150924/what-the-vw-scandal-means-f...
Germany is the home of Mercedes, BMW, and VW (which owns Porsche and Audi and is one of the largest car manufacturers in the world). Their economy is very dependent on the auto industry. They are also home to many automotive suppliers including bosch and kuka. They are also one of the largest markets in Europe.
So yeh it's all these reasons: logistics, infrastructure, talent. Plus they need German's to think of Tesla as a local brand. Imagine if Tesla is gutting market share from these other companies and they were in another country. It would engender resentment.
Plus Berlin is a cool city :-)
First off, the number of building permits did actually increase more twofold (by number of apartments) between 2012 and 2018 (the first rent control law took effect in 2015)[1].
Secondly, the rent control law doesn't apply to newly constructed buildings. So suggesting it would somehow decrease incentive to build new apartments is ludicrous. In fact the opposite is true. If you want to have higher rents, you need to construct new buildings.
[1]: https://i.imgur.com/sPgCyTn.png - screenshot because direct links don't work on that page. Source: https://www.statistik-berlin-brandenburg.de
To no one's surprise
In any case a 10% fluctuation can hardly be called "basically cut in half", as you put it. I am reading "10%" as "basically unchanged".
As it stands your argument is not even supported by the sources you are citing yourself.
Edit:
Ahah! When just comparing the single month of September we can find a decrease of about 50% though, according to the article (couldn't find a source for the number though, see below). So at least we have a number like that if we make the window so small that the data we have is beyond useful.
A 50% fluctuation on a monthly basis is perfectly normal though. For instance there was a +120% change in April 2018 / April 2019 (1517 vs 3345)[1] in total permits on a per-apartment basis. You can find plenty of such fluctuations though when just looking at months.
The data is pretty much completely useless on a month-by-month basis and can easily be skewed by a few large projects.
Also I can't figure out where that article is pulling its numbers from, because it quotes "more than 1700 permits for apartments last year in September", while the official statistics[1] just have 1301 when counting any kind of permit. For completeness, here is the press release referred to by the article, which also doesn't contain any number like that: https://www.statistik-berlin-brandenburg.de/pms/2019/19-11-0...
[1]: https://www.statistik-berlin-brandenburg.de/publikationen/St...