This is a huge problem that has bugged me for a long time, and is a problem on the iPhone too. It needs to be fixed.
Unless you can audit the code, or someone you trust has, who knows what our devices are doing.
Or you can do it the way FB does it, by asking for permission to access all your pictures and build your own non-standard picker...
Because ultimately, developers don't really need to care. Too many users don't understand the implications at all. And if it's for example a messenger that all your friends use, you don't really have much of a choice than to trust it, if you want to talk to your friends.