You're not exactly bussed to Terminal 3.....you're bussed airside to the satellite boarding area G which is connected to Terminal 3 by a subterranean shuttle train. Long story short, you go thru special (heightened security) checkin procedures at T5 which has no gates of its own and then are bussed to the same gates you would have gone thru if you went thru security at T3. Seems a bit stupid to me as anyone going thru T5 loses their sanitation when they come in contact with others at G Boarding gates that went thru T3 security, although I guess their checked luggage has had extra inspection procedures and is kept separate.