How do you know if the app requests access to your friends? Even if FB warns you about this behavior (I dont think it does) how can you trust that they won't change their policy in the future without alerting you?
Accessing your friends is not an extended permission as mentioned in another comment, any app you give permissions to can access your friends and get their ID's and Names.
You explicitly grant access for each new set of permissions - accessing a friends list (and thus their publicly available information) is one of those sets. If the site changes their policy, they have to go back to the user and request permission.
This is false - accessing the friends list only requires "basic" permissions.
The friends list can be accessed without asking for permissions via the graph API and an API key if your user id is known.