> Engine replacements are complicated. Many specific parts.

If you buy a full replacement engine (as opposed to parts to rebuild an engine), replacement is quick and easy in an ICE. In endurance racing an engine can often be replaced in less than 30 minutes. In non-racing conditions you'd do it a bit slower but it's not hard.

I would imagine that cars built for endurance racing, where this is known to be a common thing, would be designed to make it easy, while cars built for the general public will not have such a guarantee—some will be easy, some will be annoying, and some will be outright pains.

> I would imagine that cars built for endurance racing

At the higher end of professional racing, those are custom built cars.

But for most categories of racing, endurance race cars are just regular street cars. Hondas, Mazdas and BMWs are what I've raced or crewed with.