Observations of posts here over the years are pretty consistent with an equitable distribution of supply-limited (mainly newly-launched) Canon products. When a new item launches, a big shop like B&H opens preorders and a large number of people are sitting at their computers clicking Buy-Buy-Buy like Sheldon and Leonard trying to score ComiCon tickets. Others wait until the next morning and call their local shop to preorder.
When the item finally starts shipping, B&H gets lots of them, and the local shop gets a couple.
I just re-read your post. So, you only requested a stock notice? And you’re all bent out of shape? A couple weeks ago a bolus of 100-500 lenses came in to Canon USA. At least one person got their shipment from B&H of two lenses that they actually placed an order for back in May. Someone else ordered in early August (again, actually ordered not just requested a stock notice) and didn’t get the lens (but was able to buy one at Best Buy and cancel their B&H preorder).
To me, just requesting a stock notice suggests you weren’t serious about buying the lens. If you were, you’d have provided a means of payment, not just your email address. I say this as someone who did as you and requested stock notice from B&H. I was warned about slow AF performance of the lens with the EOS R (which I find to be true), and I don’t plan on seriously using the lens (for birds in flight) until I get the R3, so I wasn’t in a hurry to get it. I opportunistically saw it as ‘in stock soon’ on Amazon in mid-August, so I ordered it and received it a few days later.
I think your ire is misfocused. I don’t know how many local shop owners you’ve spoken to, I have spoken with a few. They had no issues with priority of getting stock of backordered items, they always seemed to get a few. Their beefs with Canon were more around their terms requiring prepayment for units and ever-shrinking margins. One shop owner became dissatisfied enough to quit carrying Canon photo gear, limiting their Canon sales to the Cine line (which apparently has different terms).