On the most part, bike manufacturers use standardized parts that can be replaced by and end-user with sufficient know-how and the tools to do it. There aren't that many companies making drivetrain parts, so you tend to see Shimano and SRAM just about everywhere, and maybe the odd Campagnolo-equipped bike every now and then. At least here in the US. (Unrelated, Shimano's product range is crazy - somehow their components come stock on bikes ranging from $250 up to $12k or more.)
Outside of < $200 Wal-Mart bikes, I've never had any trouble repairing or finding someone to do "normal" repairs or maintenance on a bicycle. I'd like to know what prompted the article, unless the real point was to complain about E-Bike batteries, which is not something I can really comment on.