[F87source]

Imo This dealer sounds like it is run by a bunch of idiots....

1) Some dealers will use electric ratchets that are extremely low torque to remove things, and these things have a locking mech built in so you can hand crank it to break bolts loose then press the button so it slowly unthreads a bolt. But the thing to note is they are NOT impact devices and deliver very low torques as to not damage threads. This way the technicians avoid repetitive strain injuries from doing thousands of fasteners a day. This is fine and totally normal, so long as they hand break the bolt and hand thread the bolt in and do the final torquing with a torque wrench.

2) The issue is dropping the spark plugs and joy riding the car. That should not have been done.

3) It is extremely unlikely that the plugs would ever be seized because of the special coating bosch puts onto the spark plug threads. And if it was slightly stuck it would never need as much torque as an impact will provide, that would obliterate the threads.