- The oil lubrication system, starter/alternator, various belts, and gearbox (if front wheel drive) are typically part of the engine package so don't really impact complexity.
- Liquid cooling is required for EVs if they're going to perform equivalently to a modern ICE car.
- EVs contain high voltage / high current wiring that needs to be considered carefully in terms of crash safety.
I'm not against EVs here, I think they're great. But if you want more than the old "drop a forklift motor and some batteries into a donor car" DIY build, an EV isn't actually that much simpler to assemble.