"Why doesn't this happen with other manufacturers?"

Two reasons:

- Apple cares more. Seriously, some of their engineering is unheard of elsewhere in the industry. And they have a specific focus on security that is miles ahead of everyone else.  
- Apple is vertically integrated. They control their platform throughout and make engineering decisions that intertwine parts as a consequence, because it makes sense when they can do that for various engineering reasons. For example, their LED matrix backlights are controlled by an in-SoC microcontroller, and on M2s and above the trackpad touch processing algorithms also run in-SoC. This allows them, among other things, to ship those firmwares per-OS version and not have to bother with keeping backwards compat on the interfaces, which lets them move faster and improve more easily. Practically no other manufacturer does this to that extent, usually because they outsource complete sub-modules which naturally results in simpler dividing lines that then means easier part swaps. E.g. I bet any other platform doing LED matrix backlights will have the on-screen TCON handle that processing instead.