No you don't need a UG for each founder.
Yes, this shit is complicated, but it's that way for a reason. In Germany having a GmbH is like a badge of honor and reliability. It means you are an upstanding businessman. People usually trust a GmbH more than a non-limited-liability company (GBR) even though with a GBR the founder is liable with his personal wealth without limit. Because for a GmbH you know they at least put down the 25k.
The IHK stuff is very unpopular in Germany, too. Nobody likes the IHK. It's like a guild thing from the middle ages. It's here for historical reasons. It's legacy shit we haven't gotten rid of yet.
The forms and the registers are there for a reason, too, even the Bundesanzeiger stuff. That means if you deal with a GmbH, you know the founder needed to pull their pants down in front of a public register. If you get scammed, you can find out who the proprietors are, the authorities know who they are, and they can actually be held liable.
The British tradition is very different from the German one. In Britain you could historically change your name just by using a different name. Criminals and scam artists made use of this.
The German tradition is that your name is known to the state, in fact you get an ID card with your name and photo on it. If people don't trust you, they might ask to see it. Your name is serious business. It carries weight. If someone knows your name, the law can get to you. There are no credit cards accidentally issued to dogs in Germany.
So while to you this may look like useless bureaucracy, it is really a cascaded "Are you really sure you want to do this? You will be liable for your actions. There are rules here. They will apply to you whether you know them or not."
All that said: You can actually buy a "GmbH-Mantel". Someone else did all the leg work, and you just buy the empty shell of a company which will be renamed and assigned to your name then. This can be done within a few days AFAIK.