It's hard to know why main dealers shy away from battery replacement if they have a couple of (shared) technicians. From the few videos I've watched online swapping out a battery is a couple of hours work at the outside - Ed China singlehandedly took one out, repaired it and refit it in that sort of timeframe - yet they all seem to quote 12-24 hours, presumably based on two men working on it but perhaps compensating for the space necessary preventing another two, three or four mechanics working on other stuff? I suspect transporting the batteries must be awkward, particularly disposing of the old one.
One would imagine in an ideal world they'd like to fully discharge the scrap to make it safe to handle/store ahead of recycling but I gather lithium batteries are rendered useless if they drop below c.80% of their nominal voltage so a complete discharge would remove any possibility of any modules/cells being recycled as working batteries as seems to be the green intention. I'd say it'd be interesting to calculate how much more it costs to recycle/repurpose a battery than it costs to manufacture a new one, taking all the special handling by appropriately qualified personnel at each stage of the process into account.