* the most difficult tax system in the world. even freelancers have to use accountant services, because most people will not be able to pay taxes properly without it.
* high taxes - 42% income tax + Solidaritätszuschlag 5.5% = 47.5%; for corporations it's ~30%.
* A LOT of buerocracy. I can't even send an email to tax authorities in my area, because they only accept paper letters but nothing else.
* highly qualified foreigners have to learn German and it's quite difficult language.
* the market in Germany is much smaller comparing to USA. If you want to target EU, then you have to support a lot of different languages, date/time formats, regulations and laws etc.
* recently the EU introduced a lot of additional regulations for internet companies (GDPR, new copyright directives that require checking uploaded files, etc...).
* weather is not that appealing as in the valley.
* the difference in salaries between regular developers and rockstars is very low. So there is zero motivation to become one.
* low salaries for software engineers. The most of senior software developers will earn 50.000 - 60.000 EURO anually and after paying taxes it's only ~2.600 EURO per month (3.000 USD)
* poor internet connection in a lot of places / poor connection speed - almost any country is better in this regard