Why do car companies design cars with parts that are so hard to access (e.g. bolts, etc.)?
Back in the golden era of automobiles, cars were sold with the assumption that most people would be doing their own repairs, and designed with a (mostly) logical layout in the engine compartment so everything was easy to reach, adjust, remove, and replace.
Today, service is a profit center - for franchise dealerships, the big money isn't in sales, it’s in service. The layout of the engine compartment is designed using CAD software to maximize space, require special tools, more computer-controlled functionality instead of mechanical, and generally make access to components more challenging - which encourages (and sometimes forces) more people to go to the dealer for service and buy parts directly from the manufacturer.
On many vehicles, even just replacing a factory part with an aftermarket one leads to problems. A couple years ago I was seeing an O2 sensor code in a new Jeep, so I changed it out with a brand new Bosch sensor - keep in mind that Bosch practically invented the O2 sensor, and set the standard everyone else follows. Their quality is top notch. Yet, within a day after the swap, I started seeing other error codes that had nothing to do with the sensor. Thinking maybe I had a bad one, or it was for the wrong vehicle, I replaced it again and still had weird unrelated error codes. So I have a friend pull his factory sensor, tried it in mine, and immediately the random error codes stopped. The vehicle needed a factory part to work properly. Of course, the sensor from the manufacturer was $85 vs $22 for the Bosch.
I’ve seen this happen before with other vehicles and parts too … try changing the battery out in a C6 Corvette (2005 or newer) with anything but a Delco battery, and you’ll get charging system warnings on the screen, even when the specs are identical.
And if you have a BMW or Mercedes, anyone will tell you that if you ignore the service interval light, guess what, something will need to be serviced shortly thereafter.
Follow the money trail. If something doesn't make sense to you, it probably makes perfect sense to them. It keeps their hands in your pockets.