Bicycle parts are incredibly standardized compared to cars. Outside exotic racing bikes almost every brand uses the same Shimano parts or compatible copies from other brands. And even between component brands, the way the components attach to frames are somewhat standardized so replacing an entire Shimano drivetrain with Campagnolo or vice versa is possible. The problem is that there are a bit too many standards now.
Those are the "good bikes" - the article (and I suspect the vast majority of bikes) are the Walmart specials, some of which might use standard components but much of which appear to be one-offs or similar.
It would be nice if there WAS a standard - some rating on the box indicating how "replaceable" parts on the bike are, somehow.
I'm not from the US so I can't just go to Walmart and see. What are these non-standard parts? I'm aware that cheap shock absorbers can be quite wild but what weird parts would a non-suspension bike have? Of course you don't have threaded headsets or freewheels on nice bikes but those are still available and don't have many variants.
I agree that the main reason these things aren't repaired is that a new bike costs less than a couple of spare parts and labor.
But I seriously doubt that the weird size pedal assembly is something else than bog standard Fauber crank. Those things are still made and I can't imagine how a custom part would be cheaper to manufacture.
