I have no interest in one, but playing devil's advocate, some might consider it more sanitary since you don't have to touch the toilet to flush and have the choice of not being near it, hopefully avoiding any spray.
Also, if your guests use the restroom, you can startle them at any time.
That occurred to me while writing my comment, as well, and I don't like the implications.
I would imagine they have to ask you, yes. If the toilet can be flushed without authentication, they'd probably still have to ask you how.