When Obama became President he didn't want to give up his Blackberry. The Secret Service said no problem you can use this one ONLY!
There was actually some controversy about that. Originally, they didn't want him to use a cellphone at all. That evidently hadn't been a problem with George Bush.
But Obama insisted, so they worked something out. I think what this really illustrates is that hard and fast rules about electronic devices were established piecemeal, and rather late in the game.