It's right there on the page: > Tesla Model 3 has a frameless electrochromatic mirror with no powered functionality, whereas the BMW i3 has buttons and powered

It's right there on the page: > Tesla Model 3 has a frameless electrochromatic mirror with no powered functionality, whereas the BMW i3 has buttons and powered functionality build-in. The Chevy Bold has powered functionality including backup camera display. So the Tesla just has a mirror with, presumably, one set of wires going to it to power the dimming. The others have buttons, electronics, a bundle of wires, and an LCD display in the case of the Bolt. The BoM difference probably isn't too terrible, but the cost of assembly, as well as testing/QC of those features, likely results in the cost difference. Extrapolating from that, I'd imagine that settling on one powerful touchscreen has saved Tesla some cost in a variety of places. Not just lowering BoM on things like buttons and electronics, but also ease of assembly, modularity, etc.