The bookies read the trends is all. It's the voters that are suspect...
I have a hard time believing they will vote Lamar two in a row given how negative many in the press are when he struggles; but more than that how they struggle to give him his due when he does well. I think Allen wins based on that. Lamar deserves it, but Allen will win it to round out the Big 3 QB's dominance of the MVP Award over the past few years. A 3rd MVP would indicate that Lamar is better than Mahomes, overall, and that is not a narrative the press likes.
So, in general, I think you're all overthinking this.
For me, its pretty simple:
1. The Bills have a better record. It's a gigantic piece of the puzzle. There's a reason why in modern NFL they don't give MVP awards to people who play on 8 win teams, regardless of how great they play. If Lamar Jackson played exactly the same way as he did last year, and the Ravens were the #2 or #3 seed in the conference, he's not the MVP, nor would he get many votes for it. Same reason why Joe Burrow will get little or no votes, despite being arguably the best QB in football this year.
2. There's not a dramatic difference in overall statistical measures between the two.
3. There is no person on the planet who would trade Lamar's offensive personnel for Allen's. The Bills would trade Cook for Henry, they'd trade either TE for Andrews, and Bateman and Flowers would be the top two receivers on the Bills roster if you inserted them there today. At best, the Olines are marginally the same.
4. Allen lost his best WR by a gigantic margin, and got significantly better as a player.
When you stack those things together, it's not a particularly difficult decision. The only thing that makes it "challenging", if you really break it down, is the fact that Lamar is significantly better than he was last year, and he won the award last year.