*Losing an access to a toy is not a 'consequence', it is a punishment, no more or less so than smacking. If a child refuses to go out of the house to school, for instance, there is no natural correlation between this and losing a toy.
Re your IPad example, I think it is awful that a child would believe that his continued ownership was contingent upon behaviour. So, in your eyes, is the Ipad merely loaned, rather than a gift? As, if it is a gift, it is the receiver's in law, and taking it back is theft (and you can go to jail for it if you do it to another adult).*
Ok, semantics if you fancy them.
Losing access to the iPad for 2 days is a consequence of bad behaviour
Getting a smack across your legs is a consequence of bad behaviour
One of these things will help children learn that if they are naughty, there are undesired consequences, and if they are good, there are desired consequences.
The other is hitting a vulnerable child who looks to you for safety and can't do anything about it but accept it.
In nt example, the iPad is not loaned, nor is it a gift. It is a family iPad which belongs to the family and everyone may use. However, parents can and do dictate how much time children can spend on it. That is just good sense to prevent too much screen time. If a child misbehaves, no screen time for 2 days (something they like) as a consequence of misbehaving. If they make up for it with very good behaviour, they can earn it back early. Otherwise, the set duration plays out.
They will stop being bad because they learn that they don't get access to their games or whatever.
Calling these things loans and gifts is like saying a child owns every biscuit in the tin, that was purchased during the weekly shop. They belong to the family. The parent still says you can have x amount then stop, to stop the child binging on junk.
If the child has bought the iPad outright from their own money, it cannot be used in this way. The Wi-Fi can be turned off, though.
Even If the iPad had been bought for the child, I'd like to see anyone claim theft for having it confiscated for 2 days as a result of pushing boundaries to the extreme. A friend of mine recently took her child's Xbox away for 3 days as punishment for having a tantrum and swearing at his mum, calling her a nasty fat shit. He had heard it at school and had been told before not say it again.
He hasn't said it since because he knows if he does, his Xbox goes again.