Synchronizing iCloud photo library and downloading apps over 100 MB both require wifi, ie. they are not permitted when on cellular.
Is this limit only for "convenience", so there wouldn't be surprises when the phone bill arrives? Is there any official reason? Or technical?
I'm asking this as my current cellular plan (LTE) consistently delivers better speeds than my current ADSL plan (= wifi) and I have plenty of headroom in my transfer quota.