Yes, I thought that was curious also. Although it may have been some kind of share accommodation, where locked doors to your personal area were provided.
We have blocks of student accommodation here, where their personal rooms have locking doors. They may have TVs, microwaves, electric kettles, PCs, along with their other belongings, in their rooms.
The thing that I find telling is that the housemates had not seen Alice for about 10 days. Yet Alice was free to speak with her dad on the day prior to going missing.
So exactly where was Alice when she spoke with her dad? Where was she sleeping? Had she gone away somewhere without mentioning it to her family or housemates?
Was she staying with someone who she shouldn't have been staying with? Is that why the content of the note that was found in her room cannot be disclosed? Is that why the matter is 'sensitive'?
I've seen rumors that her phone was found in her room - if this is the case, how did she speak to her father on the 30th, unless A) she used another device, like a laptop or someone else's phone, or B) her housemates are giving out false information about when she was last home (assuming she didn't manage to get her phone into the room after the 30th without them noticing)