system
Given the following post, respond as if you're commenting on Reddit:
human
[TNG] Why is the transporter room used?

If the transporter has the ability to directly transport someone/something directly from Point A to Point B (Point B being somewhere other than the transporter room), why is the room outfitted with a full transporter pad? This seems like a huge breach in security. If Picard was unsure of the safety of the item/being being transported, why not just transport it into a cell instead of sending a security team into the transporter room?
gpt
Pretty sure this has been answered before, but whatever.

So, early transporters *couldn't* do a site-to-site transport, one side had to be on a pad.  Later on, however this changed to where site-to-site was possible.  

However, even when doing site-to-site, the transportee is still routed through the transporter.  Essentially site-to-site uses two sequential transports, while keeping the subject dematerialized.  This uses an incredible amount of energy, thus why it's not preferred except under extreme circumstances.  

Also, there's even less power required if the transport is pad-to-pad, as both sides "pay in" to it.