The transporter in Star Trek has always bugged me. So many plot holes, so much nonsense.
An example: the transporter has some sort of memory buffer, which saves the signal of the person teleporting off the ship. On occasion, the crew has used that stored pattern to reconstitute a person (e.g. season one, in which Data reunited Picard’s floating spirit with his stored signal).
If this is true, why wouldn’t you store the person’s pattern until you’re absolutely sure that they’ve arrived safely on the other end? If something goes wrong with the teleportation, no problem. Just recreate the individual from the saved pattern, and go about your day.
Better yet, why not archive the saved pattern until you’re sure the crew member has returned safely from the mission? Oh, Tasha Yar died down on the planet? No worries. We’ll just restore her from the backup. She’ll be missing some memories, but she’ll be alive.