So does mine Zoomer, but not everyone's does - and anyway, we have uses for water outside which aren't just to do with watering the garden so it may be more convenient not to drain and shut off the tap - to be honest having just moved here last year we totally forgot to protect the tap, and escaped without any problems, but I don't want to risk it two years running.
And anyway, making that little device might be a lot less trouble than moving all the saucepans etc from the cupboard next to my sink where my little tap-thingy is 