I think it says a lot that in order to exploit iPhones you need to pull off what I can best describe as an exploit version of a bunker buster bomb that performs all sorts of interesting tricks to line up the chain of extremely unfortunate coincidences to exploit the platform.

Meanwhile to get RCE on a lot of Linux ecosystems you simply just need to find more places to shove the "funny bash string" in and at some point the system will probably execute it. (See, the reply, ShellShock, most LFI issues etc)