A vehicle needing a repair that costs 50% of its new MSRP is extremely rare, outside of a few electric vehicle battery packs.

In addition, when a vehicle reaches the point where any common repair costs more than it's current market value, it's basically considered worthless and only desperate people buy them. How long does it take an apple product to reach that point? A year?

Exactly. Apple has engineered their products and supply chain to make it not economically viable to do any kind of repair.

For traditional cars, as long as it's not a completely blown motor or transmission or a extensive front end collision, it's always economically viable to repair them.

You can take it to an independent repair shop. There's a supply chain of repair parts. Mercedes doesn't try to use trademark laws and DRM to stop you from using a third-party water pump.

They’ll just void your warranty for tenuously related issues, oh, kinda like…

If you have a warranty, take to it Mercedes for the warranty work. If you don't have a warranty it doesn't matter.

Additionally, you can't capriciously tell people that an unrelated repair done by a third party voided their warranty. That's a violation of the Magnuson–Moss Warranty Act.