I could be mistaken, but I think they're mostly not counting a procedure that basically amounts to loosening up a bolt that makes oil come out the bottom, tightening it back up again, and then adding new oil from the top side. I think the kind of maintenance they're thinking of is more like "replace the serpentine belt."
Timing belt is a big one for ICEs, valve adjustment if it's something racy.
There's also just so many moving parts there's far more opportunity for engine failures, especially in the face of neglect/deferred maintenance. I don't think there's an EV equivalent for needing an engine rebuild/replace because you ignored the timing belt for too long on an interference motor.
It's worse on newer ICEs that have to meet modern fuel economy and emissions standards too. Very high compression-ratios have become commonplace, making the consequences for neglect much more severe. You'd be hard-pressed to find a non-interference design in something modern. And turbo motors are much harder on their oil... Newer ICEs are tantamount to yesteryears high-strung race engines, too bad the chassis are so heavy.
Many serpentine belts are a sub-10-minute job. Put a wrench on the tensioner, take the tension off it, slip old belt off, put the new belt on, release the wrench tension. It’s literally faster than any oil change (engine, diff, or transfer case).
