So basically the difference between 9s is investment/cost.

At least here (Canada), utils push all of their costs to end-users & IIUC have an incentive to have high capex/low opex networks because of regulated return.

As a Canadian residential electrical customer, we pay a lot in base fees from what I hear relative to US customers. Sure it's more reliable, but tbh, it's not worth spending much to get 5 9s (5 mins of downtime a year) vs 4 9s (50 minutes/yr). Heck, even 500 minutes/yr would be fine for me.

But commercial/industrial users won't feel the same way, and managed to successfully spread the cost of adding 9s among users that largely don't care.