(I was hoping for a more thorough intro into pre-flight)
Well, in some places your first lesson after the trial one consists entirely of briefings, paperwork, checks, and taxying ... without actually taking off!
You don't want that on most trial flights, which are about (a) is this guy going to be sick (b) is he going to start screaming (c) is he going to like flying or find it boring (d) did he actually want this birthday present in the first place.
Most of us who've been flying for a while can now get the time from parking the car to leaving the ground down to well under an hour, provided that the plane doesn't need refuelling and that you don't have to wait for the previous person to bring the plane back and that you don't have to wait for an instructor to come back from lunch to sign the authorisation book, but you still want to skip most of that for a trial lesson. If you do take up lessons you'll soon find that you're doing all the pre-flight checks whilst the instructor stays in the warm.