Using Mercedes vs Hyundai implies that there's a difference in quality, whereas my intent was to say that they are basically the same but with qualitative differences that only matter depending on the actual circumstances.
I find that the typical answer to questions like this (e.g., the ones already given) tend to confuse the questioner even more by tossing out technical jargon out that isn't helpful.
In the end, the choice of one computing/control platform vs. another is really just which one happens to be a more suitable choice for the problem it's being thrown at.
Ultimately they're both computing platforms used for control purposes. In some cases, the predictable I/O performance of the Arduino is an advantage over the Pi. In others it's not. In some cases, the built-in network access, CPU speed, UI capability of the Pi is an advantage, in others it's not.
If Bezos actually does drive an Accord (with an entourage of security around him I imagine) then all that tells me is that for his "application," it's sufficient. It doesn't say anything about the merits of other cars.
No one needs an S-Class, it's merely a nice-to-have. Is that the same statement that no one needs this new Arduino? That they should only buy it if they have extra money to spend and want a luxury item?
They exist at different positions on the price/performance scale. It's as simple as that.