I can see it both ways too: it's fairly naive to think that uninstalling would clean-up everything like subscriptions, security settings, etc. Too many other experiences with technology would indicate this. i.e. does an uninstaller on a PC ever _really_ remove all traces of the application? And most things that we "sign-up" for like an email account, etc. also have web access regardless of the computer or phone used to create the account.
On the other hand, for an audience of mainstream users or even technical users who simply lack the specific familiarity and are assuming the apple store is a walled-garden, they should not need to have any technical experience or security knowledge to get the most reasonable outcome. For example, when I was new to Smartphones, I didn't really understand that certain permissions like OAUTH work on a global scale beyond the phone itself and that those vectors still exist after removing an app that had asked for those permissions. (Whether or not an exploit exists, it gave me chills when I realized that I had several unused instances of that still active that could hypothetically allow one service to communicate with another without me _actually_ authorizing what is going on.) I didn't even know OAUTH existed; the smartphone ecosystem simply allows apps to ask the user for it without explanation of the ramifications.
Being subscribed to a service that you decided not to use or didn't even access after the trial period is without reason; it boils down to: "ha ha, you should have known better, I'm keeping your money now."
The companion to this type of fleecing is when it is made nearly impossible to unsubscribe when the user does remember to do so... I was briefly considering XM/Sirius radio subscription (I was drawn in by the introductory rate and figured "why not"), but then a little voice told me to check how the unsubscribe works on their website... Guess what, you cannot unsubscribe at all via the website (but of course you can begin a subscription via the website.) A quick search of the web indicates that calling their service line results in nothing but tears and grief, very hard to finally get a subscription to end.