Confirmation from brother that it was unavailability of the MY and price that led to the decision - TBH, I was shocked you can't even order a Model Y in the UK yet, so probably going to be at least a year before they arrive there. As for "price", difficult to make direct comparisons, but if we assume the MY will be £5k more than the M3 then it looks to be 10-20% more expensive than the VW
They've also had a Golf and a couple of Leons in the household over the years, and like the VW brand, plus preferred the design and ergonomics of the ID4 over all the other EV's they looked - Tesla just wasn't in the frame as they don't have the form-factor they need, they don't road-trip, will be mostly local use, so charing isn't a huge consideration
Easy for us to say "wait for the MY", but I can understand his decision and as said, just happy he's moving to an EV