I realize your narrative draws this same conclusion but for clarity - "Check your tires if you want all seasons" would imply that you have any choice in the matter, like Tesla will swap them out. Not how it works. Your options are to reject the car, and hope some with Michelin appear later, or accept the Pirelli and complement or replace with a set of all seasons.So I just took delivery yesterday of my MYP and I've already experienced a problem. I didn't even think to check the tires because my buddy took delivery of his MYP just a week ago and it came with Michelin Pilot Sport All Seasons, so I just assumed that's what I would get. I accepted delivery but then when I got home, I noticed I had Pirelli P Zero summer tires. Summer tires in Nov in the PNW - how wonderful! I called Tesla to see what I can do, and my only option is to buy another set of tires for ~$2K. Since I already accepted the car, I can't reject delivery anymore (even if I could, there's no guarantee the next car would have all seasons). The person I spoke to said they're seeing both configurations being delivered - some will get all seasons and some will get summer tires. I recognize ultimately it's my responsibility and I should've checked before accepting delivery, but it would have been nice if Tesla can inform customers what kind of tires they're getting. So lesson learned - check your tires if you want all seasons.
If I had to theorycraft a few hypothesis regarding tires it's either:
a. Whatever they have in inventory during the time your car is built
b. A car was built for a buyer in a state where summers make more sense (like CA), the owner got VIN'd and cancelled, and Tesla's <next order up for that config> or whatever crazy algo chooses the next owner, then assigned and routed to a state where all seasons are more desirable.