For any hotel I've stayed in, the in room safe has ALWAYS been free.
In my post #1, the first type of safe seemed more secure (it needed a special electronic device to unlock it), than the second.
In casinos in particular, gamblers bring large sums and don't want to deal with the (inconvenience of) safes at the front desk--hence the need for secure room safes.
Even if a room safe is secure, what it's mounted to may not be: a drawer in a night stand (next to the bed), a clever theif could remove the whole drawer.