Also, Apple has the power to mandate that all apps have to run well on whatever old hardware Apple wants to keep supported. There's no good excuse.
Apples approach to extending background services was to engineer a 'motion coprocessor' to handle one class of background tasks as efficiently as possible. Samsung et al just saw the memory utilisation on their devices go up from the services they're running so they jacked up the installed memory.
The second consideration is battery life. Memory uses battery power all the time, whether that memory is doing anything useful or not. Apple is fanatical about power conservation. You don't get 10 hour battery life as a standard feature on your mobile devices by accident.
So yes Android will use more memory if there is some available but there's no evidence to suggest it needs more than iOS.
BTW, there's another class of software Android devices run that consume more RAM. UI widgets. Now that's perfectly legitimate. If you like widgets, Android or WP are the way to go. It's just that they have a cost in RAM utilization, and therefore device memory specs and power consumption. If Apple supported UI widgets, they'd have to also increase memory capacity to maintain system performance and stability, so they don't. This is an area where reasonable people can have a difference of opinion. Apple prioritize battery life and lean system design, Android emphasizes features and customization.
