US-imposed fees from YYJ and YVR are identical despite wildly different clearance schemes.

The airports aren’t dumb. They know how much preclearance benefits the carriers’ abilities to reach secondary and tertiary American markets (especially leisure). $5 a head is smart money.

I seem to recall from a white paper around the possibility for expansion in the gulf states (so this is 10+ years ago) that none of the staffing costs are borne by the participating airport - they just have to build and maintain a facility to CBP specs.