Even Costco does not always sell trees appropriate for its area. Costco in MA used to only sell ornamental trees like Japanese maples. In recent years, they have sold more fruit trees.
You should write to them but if they don’t have enough buyers, they may not be convinced.
As long as you are careful and do a bit of research, you can get some great bargains at the big box stores. Some of the prices have tempted me at times. The trees that my local Costco sold were thin, but tall and well leafed out. However, many had lots (and lots! )of algae growing in the top of their pots, a probably sign of someone watering when they didn’t know what they were doing. In the end, the cheap price wasn’t worth dealing with a small tree that had probably been serially over-watered.
However, I have bought trees and plants from other big box stores like Home Depot and have usually been pretty happy - but I’ll spend 15 minutes agonizing over exactly which tree to grab…
You’ll find a world of difference at IGCs (independent garden centers) or country nurseries.
I’m still not a fan of pottend fruit trees. Iduch rather start with seedlings or rootstock and graft.
Costco in Baxter/Brainerd has had fruit trees for at least the last two years. I’d think if they get them, your local store could as well.
They have potted mum, bulbs, little succulent arrangements, etc,but no fruit trees in the couple years they’ve been open. Rochester is a conservative town, I wonder if that has something to do with it. No clue.
I used to live up near Brainerd, back when the biggest store was Pamida. 
Seems like they’ve come a long ways, with a Costco!
If you haven’t seen what’s happened to Baxter in the last 10-15 years you won’t recognize it anymore.
My guess is that in your area there are plenty of nurseries carrying Bailey Nursery trees (Gerten’s?) and it isn’t worth it to your Costco to carry fruit trees.
Rochester conservative? You must not spend much time in rural outstate MN 
Yeah, it’s been over fifteen years now since I’ve visited!
There are two large overpriced nurseries, one of which that gets a lot of traffic. They charge over $100 per tree, but they’re large. I can’t afford that, but there’s a lot of doctors living here, so a lot of other folks can. Menards carries trees too but they never state what the rootstock is so I don’t go for it.
Rochester is changing fast, that’s for sure. When I first came here it didn’t feel too different from up North… by conservative I mean that there are a lot of people with money- country club conservative. I agree that politically things have been going the other direction, though. I get you there.