Android & File Management
In my opinion Android has always had a hard time managing photos and most people don't realise this. Probably due to its accessible storage option this occurs, so if you have any apps that takes or sends or receives any kind of media it will show up in your gallery often as duplicate in case of apps like WhatsApp where one version will be the photo you took and one will be the one you sent (compressed). So to tackle this issue of duplicate stuff, on android apps data is readable by other apps since its on a shared storage, now there is a built in option in most apps which says something like "don't show media in gallery" ; so then you can choose the stuff you want and save it manually.
The problem is the photos are still being duplicated and triplicated, all what this setting does is put a .nomedia file in the folder for that app which prevents from stuff showing up in your gallery/photos app.
Why is this an issue?
Well for one, goodluck deleting an image you took on something like WhatsApp because its normally stored at three places.
It takes extra storage.
More files mean slower phone, as quantity of files hinder processing just as much or more as size of files does.
So I don't know what Android can do to fix this issue and keep their shared nature of apps intact.
On iOS this is not an issue since every app is in a sandbox of itself and doesn't share files as readily to other apps, secondly on iOS your camera roll is the base folder for all media, so no matter how many albums you have the base folder matters only. Android did attempt this in the new google photos app and made it similar to iOS in a lot of ways but still if you open any file manager you will see how messy android's media handling system is. Just go to your local WhatsApp folder. Either android needs to restrict access to app folders or think of better ways to optimise its OS. For the average user this doesn't matter but for anyone with some tech savvy-ness, you would realise how this system of duplicating files kills your phone over time. Android phone can go only so far to increase amount of RAM in their phones, they need to start optimising software soon.