There are anecdotes from various places that suggest that drug companies sometimes try to use their economic power to influence decisions. For instance, back in 1971, when Manitoba set up its public drug plan and its formulary, the reaction from the pharmaceutical industry was that if Manitoba went ahead and did that, the industry would have to think again about investment in Manitoba.
When British Columbia set up its reference-based drug system, regardless of whether or not you think it's a good or a bad idea, the industry again made economic threats with respect to setting that up.
There were anecdotal reports when I was on the drug quality and therapeutics committee in Ontario that economic benefits were being promised should certain drugs be listed on the formulary.
I don't have any direct evidence of what goes on in Quebec or what doesn't go on in Quebec, but I believe that the enhancement or the development of the pharmaceutical industry in that province is a key aspect of its industrial strategy. So the province may feel that by listing more products it will get more economic benefit.