It's no big deal a technician taking the car home, it happens all the time & it's not just a perk of the job for them, it only happens with cars which have a problem which might have an intermittent problem and may need a longer drive to come up with the symptoms the owner has described and if the tech can get the problem to appear on a drive home then it saves the dealer losing the use of a tech during the day. A couple of times I know a tech has taken my car home in the past but I've always been asked my permission before hand, both times that was with BMW.