The problem really boils down to a combination of NIMBYism and even more importantly lobbying. Telecom lobbied the German government to allow them to not upgrade to copper cables and upgrade those with better backend infrastructure as well. However that is always going to be worse then proper fiber.
For mobile in most countries the government issues licenses with built in fines, if certain coverage quality is not reached. Germany did not do this and the conservative government even repeated that mistake with 5G. The issue is that there are only three network providers and obviously upgrades cost money, which means less profits.
Ich benutz einfach Reifen. Die vehindern das mein Boot in den Anleger crasht.....