That’s terrible. You are closer to New York and Chicago than I am.
Haha I know right! My understanding is it's due to the same regional market controls that a lot of brands started doing over the past 5-10 years, where they prohibit vendors from selling their products outside of specific territory, or advertising lower than specific prices ("MAP"). For example I used to buy a lot of Canon gear from USA (B&H) when it made sense to, however now they are prohibited by Canon from shipping to Canada. Some vendors still ignore the OEM's rules and ship it anyway, and can afford to because of the sheer volume they sell (eg Amazon).
There are ways around it, and sometimes it makes sense where there is simply no other option. For example there are several cross-border shipping services that let you use a USA-based address to order, and then you can either pick it up in the USA in person, or have it shipped onward to Canada. Obviously it comes with added cost/hassle though, so it only makes sense for me if it's something that simply isn't available locally.
And I'm still hopeful that basic print supplies aren't in that category yet... Obviously I want to be able to order consumables as I've always done: from my "local" authorized HP reseller. But if/when HP 70 / 73 supplies are truly discontinued, then I guess I'll have to either chase stuff wherever I can find it, or simply abandon the Z3X00 series (if I don't want to hack ink carts or refurb printheads to use the other Vivera ink supplies).