Earlier quoted context omitted.
Deadly force can be lawful in Germany as well, reading Texas law I wonder which nuances of the laws make the biggest difference (assuming there's one). Could also be that the difference comes from owning land works differently in Germany (because it's much more densely populated) and of course owning anything except small guns is completely forbidden.
Only when threatened and self-defense has to be proportionate. If someone attacks you with a knife you would not be allowed to defend yourself with a firearm if you had one. This is very different from the law in Texas, where, from what I understand, if you catch someone in the night stealing you could just kill them even if they never threatend you.
It's worth pointing out that night is doing some of the work in this statement. Texas is unusual, as far as I know, that darkness makes a big difference in how self-defense and danger are viewed. It kinda makes sense, because in the dark, the would-be victim is less able to fully and accurately assess the situation. So Texans need to be aware that their actions may be interpreted more harshly in the dark.