I usually fly Air NZ or Singapore out of Auckland and both airlines always require either verification of a visa or return ticket within the 30 day visa free entry. Maybe buy a flexible return ticket - cheaper than a last minute purchase at the airport.
My visa goes from $300NZ (approx. 6,600 Baht) to $2,000NZ (approx. 44,000 Baht), about a 570% increase! There is no way to justify this under Cost of Living increases or exchange rate movement (the NZ dollar has stayed within a range of 20-22 Baht for years). Will be interesting to see how other countries are affected.
That's part of the online check in process - if your passport/visa needs verification then you cannot complete the process and are directed to report to the check in counter. As she is returning to her home country, she should have no issues completing the online check in and accessing her boarding pass.
If you check in on-line and print your boarding pass, you can bypass the check-in counters and go straight to security/immigration (have done it personally).