750XL you may be right but on the day it all went smoothly. Knowing they were going nowhere fast they unloaded the bags onto the tarmac, then off loaded the pax (by row numbers) and they identified their bags. The bags were then loaded on baggage carts and the pax bussed to the terminal (we were on a remote stand). Remember, these were the days when airline staff were encouraged to use initiative and had the brains to ORGANISE. Sadly lacking these days!
Maybe that was possible back 'in the day', but not these days.
Firstly you need the equipment and a ramp team to offload the thing, then take all the bags out of the cans and line them up in some sort of fashion on the apron. You're probably looking at a minimum of 5 guys, 1 hi-lo, various EBTs and dollies. Once that's done, you'll need a few passenger service staff to escort the passengers off the aircraft to ID their bag, get the bag put to one side then load the passengers back onto the aircraft (up rear steps presumably) or onto a coach. The airport probably won't be able to afford to have a few coaches sat at the aircraft side for an hour or more while this is done. On top of this, you're going to need someone to load plan it for the onload of ULDs, then get a loadsheet prepared (unless the captain decides to do it himself). Where I work, and I'd imagine all other airports in the UK, handling agents can barely cover their own scheduled flights never mind diverts sat on the apron having bag ID's.