Yes, I believe you hit a limitation of the kiosk check-in process.

What country issued the passport you scanned?

It's a Saudi passport, so my green card is my "visa" to Canada, so to speak.

Mexico and Costa Rica, based on personal experience. Green card holders are also allowed to transit through Schengen countries visa-free.

Does the PNR include a ticketed return leg to the US within 6 months?

Full list:

https://en.wikipedia.org/wiki/Lawful...nent_residents

I think so? It was a 4-day return trip with separate tickets, one on United and the other on Air Canada.

As I mentioned before, this didn't hinder my ability to enter Canada itself, but United's online check-in and airport kiosk were awkward because they didn't ask to provide my eTA number or my permanent resident number, even though I entered my NEXUS card number, which conveys that I'm visa-free to Canada anyway.

Separate tickets? This may have dinged you at the kiosk. If the system was only able to see the OW to Canada, it may not accept your Green Card, as it wouldn't be valid for a stay > 6 months and the system has no way of knowing how long you will stay.

I'm not completely certain because neither the online check-in nor the kiosk at any point of the process asked me at all if I had a green card even. It was the same when I flew to Toronto 3 years ago on the same airline/ticket/confirmation number for a weekend roundtrip.

I'm confused. Why would a kiosk ask a Saudi passport holder traveling to Canada if he/she has a US Green Card?

A green card is the quickest way to verify someone is visa-free for Canada. Since the destination is Canada, the kiosk ought to ask if non-visa-free traveler if they have a visa or a permanent residence card or something. Even TIMATIC asks what kind of residential document a traveler has if they put in a country of residence that doesn't match their nationality. If you put USA as country of residence on there (or any other country of residence, really), one of the options to choose from under is the green card. It's one of the quickest ways to ensure someone is visa-free for Canada.

The check-in process for United and the airport kiosk ask about country of residence, which I put as USA, but afterward they doesn't ask to input anything further, yet TIMATIC does.

This really is the crux of what I'm getting at. Other airlines (from the little remember) allow travelers to input their green card numbers or even eTA.

So I was wondering if anyone in my situation was able to streamline the process or if it turns out I used the kiosk incorrectly or something.

I did send an email to United about this, but it'll probably be a while before I hear anything from them. I doubt there's anything current I can do to circumvent needing to see an agent when checking in for a flight to Canada, which can be a pain if the lines are too long.

Okay, I understand that element of the process. However, these kiosks are checking in people traveling to who knows how many countries around the world. Certainly not just Canada. So this GC issue for a non-visa waiver national still seems like a small item in the big scheme of things... one that a real agent might be best to handle.

Since the flight was headed to Canada, I assumed the process would highlight the requirements for that specific destination. Even when I went to the bag drop and the agent came in and put her employee number on or something on the kiosk that was refusing to check me in, TIMATIC requirements showed up. I showed her the green card and I told her I have an eTA (she didn't ask for proof of the eTA but I was asked for it at the gate itself).

Either way, I'm glad my NEXUS card makes things a bit easier and I can hardly wait to get US citizenship so this hassle can be mitigated.

Yes, I'm sure the #1 perk of gaining U.S. citizenship will be using the kiosks to check in for United flights to Canada! :)